GASTEROPODA. 155 



Distr., 100 sp. Brit., Norway, &c. World-wide. 



Fossil, above 100 sp. of patellidse, including acmaa, L. silurian . N. 

 America, Europe. 



Sub-genera. Nacella, Schum. (=patina, Leach.) Example, P. pellucida. 

 PL XI., fig. 23. Shell thin; apex nearly marginal. Animal with the mouth 

 entire below. Branchiae not continued in front of the head. Found on the 

 fronds and stalks of sea-weeds. Brit., Cape, Cape Horn. 



Scutellina, Gray. S. crenulata. Shell with a broad margin, internaDy. 

 7 sp. lied Sea Philippines Pacific Panama (Cuming). 



Metoptoma, Phillips. M. pileus Ph. Shell limpet-like, side beneath the 

 apex truncated. Resembling the posterior valve of a chiton. 7 sp. Carb. 

 limestone. Brit. 



ACM.EA, Eschscholtz. 



Etym., acme, a point. 



Syn., tectura, M. Edw. Lottia and scurria, Gray. Patelloida, Quoy. 



Type, A. testudinalis. PI. XI., fig. 24. 



Shell like patella. Animal with a single pectinated gill ; lodged in a 

 cervical cavity, and exserted from the right side of the neck when the crea- 

 ture walks. Lingual teeth 3 on each side of the median line. Low-water to 

 30 fms. (Forbes.) 



Distr., 20 sp. Norway, Brit., Australia, Pacific, W. America. 



Sub -genera. Lepeta, Gray (= pro-pilidium, Forbes). Patella cseca, 

 Mull. Shell minute, apex posterior. Animal blind. Brit. 30 90 fms. 



Pilidium, Forbes. P. fulva, Milll. Brit. 2080 fathoms water. Shell 

 small, apex anterior. Animal blind ; gills 2, not projecting ; mantle even- 

 edged. Both lepeta and pilidium have large single median teeth, with trilobed 

 hooks ; and 2 hooked uncini on each side. 



GADINIA (Adanson), Gray. 



Type, G. peruviana. Plate XI., fig. 26. Syn., mouretia, Sby. 

 Shell conical; muscular impression horse-shoe shaped, the right side 

 shortest, terminating at the siphonal groove. 



Animal with a single cervical gill ; tentacles expanded, funnel-shaped. 

 Distr., 8 sp. Medit., Red Sea, Africa, Peru. 

 Fossil, 1 sp. Sicily. 



? SIPHONARIA, Blainville. 



Type, S. sipho. PI. XL, fig. 25. 



Shell like patella; apex sub -central, posterior; muscular impression 

 horse-shoe shaped, divided on the right side by a deep siphonal groove, which 

 produces a slight projection on the margin. 



