OF MOLLUSCA. 173 



edge entire, strong, arrow-shaped, the middle point strong, with a 

 minute basal one on each side ; lateral teeth elongated, hooked ; 

 hook long, lanceolate, outer margin ciliated. 



Suborder VI. Cyclobranchia. 



Gill lamellar, on the inner surface of the mantle, forming a more 

 or less complete ring just beneath the margin. Side of foot with a 

 sunken groove. Shell conical, symmetrical. Teeth in ten or eleven 

 longitudinal series ; the two inner close together, the three lateral 

 series close and lower down, forming an arched or double cross series 

 (p. 169). 



Fam. XIV. PATELLID^. 



Shell simple, conical ; apex subanterior. Aperture ovate or ob- 

 long. The gills are only an elongated branchial plume springing 

 from the neck, and ought not to be looked on as a pair of symmetrical 

 subsemicircular laminae, as in the Cyclobranchiate Chitons. 



M. Cuvier and most other naturalists consider the laminae placed 

 round the edge of the under side of the mantle as gills, but M. de Blain- 

 ville doubts this being the case, and considers some vessels which he 

 has observed on the inner surface of the mantle over the back of the 

 neck as the true gills of these animals, and he has accordingly formed 

 them into a family under the name of Retifera. 



I have not been able to observe any peculiar vascular structure in 

 the part indicated ; and as the laminae round the edge of the mantle 

 exactly agree in texture with the laminae similarly disposed in Phyl- 

 lidia and Chiton, which M. de Blainville considers as gills, I have 

 little doubt but that the latter are true gills. 



According to M. Rang, they seldom change their place on the 

 rock, and then only in the night. 



These animals are very abundant on the rocks, and our English 

 species is much sought after for food and as bait by the fishermen 

 and others who live on the coast : and the large species which are so 

 abundant at the Cape of Good Hope are collected by the English 

 soldiers and by the Hottentots to make soup of. 



Adanson speaks of the beauty and delicacy of form of the fringe 

 of tentacula which surrounds the edge of the margin of the mantle 

 of the animal of this genus. In the species which he mentioned 

 there were three rows of them, each containing above 200 tenta- 

 cula. 



Adanson observed some minute globes on the surface of the foot 

 of one of the species of this genus, which he believed to answer as a 

 sucker to attach the animal to the rocks (Senegal, p. 30). 



