CYCLOBRANCHIATA. 
145 
Fam. 2. Patcllida. Gills forming a row of leaflets surrounding the body. 
No cervical plume-lilte gill. Genera; Ancistromemsy Patella, Pati- 
nclla, Nacella, Ilchion, Hclcioniscus, and Patina. 
Tecturid^e. 
Acma?a, Eschsclioltz. This genus is subdivided by Dali, Am. J. Conch, vi. 
pp. 237-200, in the following manner : — 
Acmoia, Esch. Type A. mitra, Esch. 
Collinclla, subg. n. Lateral teeth unequal, muzzle-frill simple. 
Sect. a. One mncinus: C. pelta (Esch.), patina (Esch.), tcstudinalis 
(Miill.), persona (Esch.), spectrum (Reeve), scabra (Reeve), asmi 
(Midd.), mitclla (Menke), strigatella (Carpenter), (Menke), 
paleacea (Gould), atrata (Carp.), pediculus (Phil.), suhrugosa (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.7>. Collinsellma. Two uncini : C. saccharina (L.) and horneensis 
(Reeve) ; dentition of both figured pi. 15. f. 17 and 18. 
Acmeea sgharitica, sp. n., Dali, 1. c. p. 257, pl.J7. f. 34, Rohring’s Strait, in 
deep water ; A. hicrosolymitana, sp. n., Dali, 1. c. p. 258, pi. 17. f. 87, China. 
Both belong probably to the first section of Collinella. 
Acmcea concinna, sp. n., and A. schrenckii (Lischke) redescribed, Lischke, 
Mai. Bl. xvii. p. 26, 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. Dali, 1. c. p. 200, 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 
(Lqbq.)— pallida (Sow.). To this genus belong also mesoleuca, Menke, pi. 15. 
f. 19, and probably also zehrina, Less. Dali, 1. c. p. 262. 
Patellid^e. 
Ancistrornesus, gen. nov., Dali, 1. 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. 10. f. 21. 
PatincUa, gen. nov., Dali, 1. 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 (GmjA.) =ideaurata (Gmel.) (Wood); 
dentition figured pi. 16. f. 24. 
Nacella, 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.) = cowcArtccrt (QmQ\.') — mytiloides (Schumacher) 
(Lam.), common on floating fuci near Cape Horn. Dali, /. c. p. 274; den- 
tition pi. 16. fig. 2. 
Helcioniscus, gen. nov., Dali. 1. 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)=s«nc?- 
wicensis (Pease) ; dentition of all three figured pi. 16. figs. 27-29. 
