PATELLID^:. 331 



Lepeta, Gray. 



Syn. — Cryptobranchia, Midd. pars. Propilidium, Gray, not 

 Forbes and Hanley. Pilidium, Stimpson, not F. and H. nor 

 Midd. 



Shell conical, patelliform, with a subspiral nucleus, which is 

 generally lost in early life, the permanent apex being erect or 

 anteriorl}^ directed. 



Animal without eyes, without lateral teeth, with a rachidian 

 tooth, and erect uncini ; muzzle with an entire margin, which is 

 extended backward into a tentacle-like filament on each side. 



LEPETA (restricted ) , Dall. Apex erect. Rachidian tooth tri- 

 cuspid, the middle cusp much larger ; lateral teeth simply cuspi- 

 date. L. cseca, Miill. (Ixxxiv, 42;. 



CRYPTOBRANCHIA (restricted), Dall. Apex inclined anteriorly, 

 Rachidian tooth .with three nearly equal denticles ; uncini 

 broadly hooked. L. concentrica, Midd. (Ixxxiv, 43). 



LEPETELLA, Yerrill. Shell as in Lepeta. Animal difi'erlng in 

 having eyes and in being provided with true lateral teeth and 

 also with scale-shaped uncini. L. tubicola, Verrill. 200 to 400 

 fms., off New England coast. 



PILIDIUM, Forbes. (lotha, Gray. Ergina, Jeffreys.) Shell 

 patelliform, apex anterior, generally deep-colored. Mantle 

 fringed with cilia ; rachidian tooth long, rhomboidal, bearing a 

 very large black cusp with a simple denticle on each side, laterals 

 with broad cusps striated beneath and obliquely bent, shafts 

 slender. P. fulvmn, Forbes. Northern America and European 

 coasts. 



Subfamily AGMMIN^. 



Embryonic shell conical. Animal usually having eyes and 

 a plumose, cervical, external gill, with or without a marginal 

 cordon ; rachidian tooth rarely present, lateral teeth three in 

 number. 



AcM^A, Esch. 



Syn. — Tectura, And. Patelloida, Quoy and Gaim. Lottia, 

 Gray. lotha, Forbes. Patelloidea, Ooattr. Tectura, Gray. 

 Scutellina, Gray. Scutella, Brod. 



Bistr. — 25 sp. Mostly W. Coast of N. America, Europe, etc. 

 A. mitra, Esch. (Ixxxiv, 44). 



Shell solid, patelliform ; apex erect or anteriorly inclined. 

 Animal. Muzzle frilled, produced at the lower anterior corners 

 into two lappets or tubercles ; no marginal cordon, the cervical 

 gill alone present. 



COLLISELLA, Dall. Muzzlc-frill simple, entire, not produced 

 into lappets or tubercles. A. spectrum^ Reeve (Ixxxiv, 45, 46). 

 A. variabilis, Sowb. (Ixxxiv, 47). 



