ECHINODERMATA - KU ScholarWorks - University of Kansas

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1 1 0 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS new genus; so-called Metablastus hispanicus of the Devonian of Spain, probably does not belong to this genus; forms identified as Orbitremites aplatus, O. calycinus, O. excavatus, O. fimbriatus, O. grandis, O. magnificus, O. ornatus, O. parvus, O. spathatus, O. spinuliferus, and O. tvachsmuthi probably belong to diverse genera, some perhaps to new genera, but seemingly not to Orbitremites; Phaenoschisma? kentuckyense probably does not belong to Phaenoschisrna. It is hoped that others will restudy blastoids in collections of various museums in order to fill in gaps in knowledge such as are here suggested. It is significant that very few blastoids have been described from Pennsylvanian deposits and that records of blastoids in South America, Africa, Antarctica, Asia, and the North Polar regions are meager or lacking. Evidently the study of blastoids is not yet far advanced. It is premature to say that the center of dispersal of blastoids is the mid-Continent region of the United States, merely because the oldest and most primitive blastoids occur in Silurian deposits of this region. The basis for this sort of statement is that Silurian blastoids have not been described from other continents, but it would not be surprising if they are discovered in various regions outside of North America. There is little in common between blastoid genera of Europe and North America, or between those of Timor and Europe, or between Timor and North America, and yet when lineages are traced, a tie between these regions seems to exist. "Missing links," both stratigraphic and geographic, are postulated to account for the differences; when missing links are found, the literature on blastoids will probably be double its present size. To date, approximately 800 articles have been published on blastoids; they treat some 33 genera of the Fissiculata and 35 genera of the Spiraculata, together including about 350 species. KEY TO FAMILIES AND GENERA OF BLASTOIDEA The following key is offered as an aid to those who may wish to identify genera of blastoids, as now known and understood. The key is arranged by families belonging to the two orders Fissiculata and Spiraculata. In using the key, one should proceed by noting the characters recorded under succesive letters and numbers until the desired end is reached. Hydrospire fields exposed or spiracular slits present FISSICULATA Hydrospire fields concealed, pores and spiracles present SPIRACULATA FISSICULATA [Families, see nos. 1-5] 1. Exposed hydrospire fields ten (Phaenoschismatidae) A 2. Exposed hydrospire fields nine (Brachyschismatidae) 3. Exposed hydrospire fields eight (Codasteridae) 4. Spiracular slits ten (Orophocrinidae) D 5. Spiracular slits eight (Astrocrinidae) SPIRACULATA [Families, see nos. 6-10] 6. Spiracles five, simple (Pentremitidae) 7. Spiracles five, paired (Troosticrinidae) G 8. Spiracles nine (Granatocrinidae) H 9. Spiracles ten, anus separate, cryptodeltoids exposed (Nucleocrinidae) 10. Spiracles ten, anus separate, cryptodeltoids absent (Schizoblastidae) A. PHAENOSCHISMATIDAE (Silurian-Permian) [Genera, see nos. 11 -311 11. Anal deltoids four to six 14, 15 12. Anal deltoids three Decaschisma 13. Anal deltoids two or one 16, 17 14. Hydrospire slits reduced in number on anal side Deltoschisma 15. Hydrospire slits not reduced in number on anal side 18, 19 16. Ambulacra with lancets widely exposed Phaenoblastus 17. Ambulacra with lancets covered by side plates 22, 23 18. Ambulacra directed laterally outward, six anal deltoids Polydeltoideus 19. Ambulacra directed downward, four anal deltoids 20, 21 20. Hydrospire slits completely exposed .. Pleuroschisma 21. Hydrospire slits almost hidden, with formation of pores Hyperoblastus 22. Ambulacra five 24, 25 23. Ambulacra two Dipteroblastus 24. Ambulacra extremely long 26, 27 25. Ambulacra moderately long to extremely short 28, 29 26. Ambulacra flaring outward into elongate wings Thaumatoblastus 27. Ambulacra projecting downward aborally, calyx globular Nymphaeoblastus 28. Ambulacra moderately long 30a, 30b, 31 29. Ambulacra extremely short Neoschisma 30a.Calyx conical, ambulacra narrow Con oschisma 30b. Calyx conical, ambulacra broad Phaenoschisma 31. Calyx flattened Notoblastus
BLASTOID STUDIES 111 B. BRACHYSCHISMATIDAE (Devonian) [Genus, see no. 32 1 32. Hydrospire field on left "D" side of anal opening atrophied Brachyschisma C. CODASTERIDAE (Devonian-Permian) [Genera, see nos. 33-42] 33. Anal deltoids three or at least two invariably present along with subdeltoid Trionoblastus 34. Anal deltoids two or at least one invariably present, subdeltoid absent 35, 36 35. Hydrospire slits extending onto radials 37, 38 36. Hydrospire slits restricted to deltoids .. Paracodaster 37. Radials with winglike projections Pterotoblastus 38. Radials lacking winglike projections 39, 40 39. Hydrospire fields wide Codaster 40. Hydrospire fields restricted 41, 42 41. Deltoids long, lancet-shaped, with small hypodeltoid Angioblastus 42. Deltoids wide, arrow-shaped, seemingly without hypodeltoid Sagittoblastus D. OROPHOCRINIDAE (Mississippian-Permian) [Genera, see nos. 43-56] 43. Spiracular slits long 45, 46 44. Spiracular slits short 47, 48 45. Lancet widely exposed Anthoblastus 46. Lancet mostly covered by side plates 49, 50 47. Lancet close to oral opening Sundablastus 48. Lancet moderately distant from oral opening ..51, 52 49. Hypodeltoid large Orophocrinus 50. Hypodeltoid small or lacking 53, 54 51. Winglike interradial projections on calyx Tim oroblastus 52. Winglike interradial projections lacking 55, 56 53. Anal opening restricted to single deltoid Pen tablastus 54. Anal opening adjacent to radial limbs, possibly with an atrophied hypodeltoid Sphaeroschisma 55. Ambulacra moderately short, hypodeltoid possibly atrophied Microblastus 56. Ambulacra moderately long, large hypodeltoid present lndoblastus E. ASTROCRINIDAE (Devonian-Permian) [Genera, see nos. 57-66] 57. Slits elongate along lancet 59, 60 58. Slits extremely small, confined to summit 61,62 59. Ambulacra five, normal 63, 64 60. Ambulacrum "D" extremely short, other four long 65, 66 61. Calyx shape steeply conical, extremely narrow Ceratoblastus 62. Calyx shape bluntly conical, hypodeltoid large, ambulacra extremely short .. Nan noblastus 63. Lancet covered by side plates Pentremitidea 64. Lancet completely exposed Cry ptoschisma 65. Radials bluntly winglike, three basais present Pentephyllum 66. Radials concave inward, single basal present Astrocrinus F. PENTREMITIDAE (Devonian-Permian) [Genera, see nos. 67-84 1 67. Deltoids four, not visible in side view Cordyloblastus 68. Deltoids visible in side view 69, 70 69. Ambulacra five, normally developed 71,72 70. Ambulacra five, ambulacrum "D" shorter than others Eleutherocrinus 71. Hydrospire plate present, two pores to each side plate 73, 74 72. Hydrospire plate absent, pores simple 75, 76 73. Calyx globular, two hydrospire folds on each side of an ambulacrum Globo blastus 74. Calyx globular, single hydrospire fold on each side of an ambulacrum 77, 78 75. Calyx club-shaped, base pyriform, orals small 79, 80 76. Calyx elongate-elliptical, with five large orals Ambolostoma 77. Radials overlapping deltoids Ellipticoblastus 78. Deltoids overlapping radials Orbitremites 79. Anal deltoids two or more 81, 82 80. Anal deltoid single 83, 84 81. Lancet completely exposed, two anal deltoids Petaloblastus 82. Lancet covered by side plates, four anal deltoids Devonoblastus 83. Anispiracle adjacent to oral opening .... Pentremites 84. Anispiracle adjacent to radial limbs Rhopaloblastus G. TROOSTICRINIDAE (Silurian-Mississippian) [Genera, see nos. 85-92] 85. Calyx conical in side view 87, 88 86. Calyx globular Diploblastus 87. Deltoids not visible in side view 89, 90 88. Deltoids plainly visible in side view .. Schizotremites 89. Ambulacra directed outward, pelvis long Troosticrinus 90. Ambulacra directed downward, pelvis long or short 91,92 91. Pelvis steeply conical, hydrospire folds four or five on each side of an ambulacrum Metablastus 92. Pelvis bluntly flaring, with three short hydrospire folds in radials on each side of an ambulacrum Tricoelocrinus
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