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CYCLOBRANCHIATA. 145
Fam. 2. Patellidce. Gills forming a row of leaflets surrounding the body.
No cervical plume-like gill. Genera: Ancistromesus, Patella, Patinella,
Naeella, Helcion, Helcioniscus, and Patina.
TECTURIDJE.
Aemcea, Eschscholtz. This genus is subdivided by Dall, Am. J. Conch, vi.
pp. 237-260, in the following manner :—
Aemcea, Esch. Type A. mitra, Esch.
Collinella, subg. n, Lateral teeth unequal, muzzle-frill simple.
Sect. a. One uncinus: C. pelta (Esch.), patina (Esch.), testudinalis
(Miill.), persona (Esch.), spectrum (Reeve), scabra (Reeve), asmi
(Midd.), mitella (Menke), strigatella (Carpenter), fascicularis (Menke),
paleacea (Gould), atrata (Carp.), pediculus (Phil), subruyosa (Orb.),
and araucana (Orb.); the dentition of all these, except paleacea and
araucana, figured pi 14. figs. 4-15, and pi. 15. fig. 16.
Sect. b. Collinsellina. Two uncini: C. saccharina (L.) and borneensis
(Reeve) ; dentition of both figured pi 15. f. 17 and 18.
Aemcea sybaritica, sp. n., Dall, I. c. p. 257, pi. 17. f. 34, Behring's Strait, in
deep water; A. hierosolymitana, sp. n., Dall, 1. c. p. 258, pi 17. f. 37, China.
Both belong probably to the first section of Collinella.
Aemcea concinna, sp. n., and A. schrenckii (Lischke) redescribed, Lischke,
Mal. Bl. xvii. p. 25, both from Japan.
Lottia, Gray. This genus is distinguished by the presence of a branchial
cordon around the posterior half of the body, continuous behind, and reaching
forwards as far as the shell-muscle, besides the cervical gill. Dentition of
Lottia gigantea, Sow., described and figured. Dall, I. c. p. 260, pi. 15. f. 20.
Scurria, Gray. This genus has also besides the cervical gill an accessory
branchial cordon, which goes round the body as in Patella. Type S. scurra
(~Less.)=pallida (Sow.). To this genus belong also mesoleuca, Menke, pi. 15.
f. 19, and probably also zebrina, Less. Dall, I. c. p. 262.
PATELLIDCE.
Ancistromesus, gen. nov., Dall, /. c. p. 266. A simple rhachidian tooth;
two inner lateral teeth on each side anterior to the third, which is large and
quadridentate. Uncini simple. A. mexicanus (Brod. and Sow.); dentition
figured pi 16. f. 21.
Patinella, gen. nov., Dall, I. c. p. 272. Sides of the foot provided with
scalloped lappets. Teeth 3 (2-1 . 1-2) 3. Inner uncinus plate-like, without
a cusp. P. magellanica (Gmel.)= deaurata (Qmel.)=ferruginea (Wood);
dentition figured pi. 15. f. 24.
Naeella, Schum. This genus also has scalloped lappets on the sides of the
foot. The second and the third lateral teeth are large and subequal N.
mytilina (Gmel) = conehacea (QrA&l.) = mytiloides (Schumacher)=cymbularia
(Lam.), common on floating fuci near Cape Horn. Dall, I. c. p. 274; dentition
pi 16. fig. 2.
Helcioniscus, gen. nov., Dall. I. c. p. 277. Inner uncinus hardly raised above
the level of the ribbon; second lateral tooth largest. Sides of the foot
smooth. H. variegatus (Reeve), rota (Reeve), and exaratus (Nuttall)=«mdwicensis
(Pease) ; dentition of all three figured pi. 16. figs. 27-29.