of the Order Docoglossa. 287 



tomical investigations upon my part, which, so far as I am 

 aware, are the only ones, including the whole order, which 

 have been made. I am indebted to Prof. Gill for suggesting 

 the very appropriate names by which I have designated the 

 suborders as restricted. 



Class GASTEROPODA. 



Order DOCOGLOSSA, Dall ex Trosch. 1870. 



Suborder ABRANCHIATA (Gill), Dall, 1870. 



Radula furnished with a rhachidian tooth and two uncini. 

 Animal destitute of eyes, branchiee, and lateral teeth on the 

 area. 



Family LepetidaB (Gray), Dall, 1869. 



Shell patelliform ; apex erect or anteriorly directed. Muzzle 

 of the animal with an entire edge ; furnished with a tentacular 

 appendage below on each side. 



Formula of the radula, jT^T^y-g- 



Genus Lepeta, Dall ex Gray, 1869. 

 A. LeiMa^ Dall. 



Rhachidian tooth tricuspid, concave in front ; central cusp 

 simple, much the largest ; lateral cusps small, emarginate, 

 base very broad ; uncini with simple cusps. 



Type Lepeta cceca (Gray), Dall, Am. Journ. Conch. 1869, 

 v. p. 141. 



B. Cryptohranchiaj Dall ex Midd. 1869. 



Rhachidian tooth with three short cusps, equal and parallel 

 before and behind, not pointed ; base moderately broad, more 

 or less ornate behind ; uncini with simple cusps. 



Type Gryptohranchia concentrica (Midd.), Dall, Am. Journ. 

 Conch. 1869, v. p. 143. 



c. Ftlidmm, Dall ex Forbes, 1869. 



Rhachidian tooth tricuspid, central cusp much the largest, 

 convex in front ; lateral cusps simply pointed ; base narrow ; 

 uncini Avith cusps obliquely twisted. 



Type Pilidium fulvuui (Forbes), Dall, Am. Journ. Conch. 

 1869, V. p. 146. 



. Suborder PROTEOBRANCHIATA, Dall, 1870. 



Animal provided with three lateral teeth, with <^y^^^ and 

 with external brancliia^. Rhachidian tooth usually wanting. 

 Uncini present or absent. 



