History of British animals - University of Guam Marine Laboratory

234 MOLLUSCA. CErHALOPODA. Arethusa.depression is observable, and produced by the margin of the last chamberrising on the side of the second. The chambers are rounded externally.18. V. subrotundum.— Mouth depressed, toothless.Serpula subrotunda dorso elevato, Walk. Test. Min. t. i. f. 4.— Ver. sub.Mont. Test. Brit. 521. Flem. Wern. Mem. iv. 5G5. t. xv. f. 5.— Commou.Globular, chambers three, rarely four, inflated and wrinkled. The fourthchamber, when present, seems always imperfectly formed.19- V. blcome.— The last formed chamber striated longitudinally.Serpula bicornis ventrieosa, Walk. Test. Min. t. i. f. 2 Ver. bicorne,Mont. Test. Brit. 519.— Sandwich and Reculver, Mr Boycs.Length one line ;chambers three, the middle one small, raised or depressed;the last chamber is suboval, compressed, striated longitudinally on thelonger side from the aperture the other side is smooth ; : It contracts towardsthe mouth, which is very small and orbicular.These species belong to the genus Milista of Lamark, instituted many yearssubsequent to the Vermiculum of Montagu. The fossil species of France arenumerous.Gen. VII. ARETHUSA ?{of Montfort).— Cells arrangedobliquely and alternately along an axis, with the mouthsof all the chambers having an aspect towards the samepole ;forming a subturriculated shell.20. A. lactca.— Chambers ovate, aperture circular.Serpula tenuis ovalis hevis, Walk. Test. Min. t. i. f. 5 Vermiculumlacteum, Mont. Test. Brit. 522. Flem. Wern. Mem. iv. 566. t. xv.f. 6.— Among corallines, English and Scotch coasts.Length about 5'uth of an inch, delicately transparent, with the inner wallsof the chambers appearing as white veins. The chambers are six or seven innumber, well defined on one side, obscure on the other, contracted towardsthe mouth. Walker and Montagu obtained this species at Sandwich andDevon, Captain Laskey at Dunbar, and I have it from Leith and Zetland.Gen. VIII. LAGENULA—Shell with a globular body, havinga producedneck or tube.* With longitudinal markings.21. L. striata.— Shell pellucid, with opake, fine, longitudinalstriae.Serpula (Lagena) striata sulcata rotundata, Walk. Test. Min. t. 1. f. 6.—Vermiculum striatum, Mont. Test. Brit. 523.— Not uncommon insand on the English shores.In shape, this species resembles a Florence flask ; rounded retrally ;themouth is slender and produced, with a small round aperture ; length nothalf a line.