PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 319 



Leptochitoa nexus. 



L. nexus Cpr. Suppl. Kep. Br. As. 180:3, p. 650. 

 Hah. — California, Cooper. 



Leptochitou iuternexus aud var. rugatus. 

 L. infeniexus Cpr. MSS. 

 Rah. — California, Cooper, Canfield and HempliiH. 



Hanleyia mendicaria. 



Chiton mcndkariun Migliels &. Adams, Boston .lonru. N. H. iv, p. 42, pi. iv, 



f. 8, 1842. 

 Hanleyia mendicaria Cpr. N. Engl. Chitons, 1. c. p. 154, 1873. 



Rah. — Casco Bay; Grand Manan, Stimpsonj Portland Harbor, Me., 

 U. S. Fish Commission. Deep-water specimens much larger than those 

 from shallow water. 



Hanleyia debilis. 



Hanleyia debilis Gray, Guide, p. 186, 1857. 



Chiton Hanleyi Bean, Brit. Mar. Conch, p. 262, f. .57, 1844. — Sars, 1. c. p. 109, 

 pi. 7, f. 5 a-i, 1878. 



Rah. — British seas northward; Mageroe near Ii^orth Cai)e, 25-300 f., 

 Sars. Stellwagen Bank, Mass. Bay, 38 fathoms, gravel; U. S. Fish 

 Com., 1878. Type of the subgenus. A recent addition to our North- 

 east American fauna. 



Hanleyia (?) abyssorum. 



Chiton abyssorum M. Sars, MSS.— G. O. Sars. 1. c. p. 109, pi. 7, f. 4 a-c, pi. I, 

 f. 6 a-i-, 1878. 



Rah. — Bergen, Norway, 150-200 fathoms, Sars, 1. c. 



The teeth of this species as figiu'ed by Sars agree pretty well with 

 those of R. mendicaria, but neither Prof. Sars' figures nor his descrip- 

 tion afford means for determining its generic position. The valves of 

 the two specimens figured exhibit rather remarkable difiterences, and, 

 this variation admitted, the question arises, Is this more than a gigantic 

 form of the preceding ? 



Hanleyia tropicalis. 



A large and beautiful species from the deep waters of the Gulf of 

 Mexico is the only other recognized species of the genus, and will be 

 described bj'^ the writer in the Eeport on the Deep-sea Dredgings made 

 under the supervision of Prof. A. Agassiz, on the U. S. Coast Survey 

 steamer Blake, in 1878. 



ISCHNOIDEA. 

 Genus TRACHYDEKMON Cpr. 



Traehydei-mon Cpr. Suppl. Eop. Br. As. 1863, p. 649, as a subgeifus of Ischnochiton , typo 



Chiton cincrens Lowe. 

 Lepidopleurivs sp. auct. 

 > Craspedochilns G. O. Sars, 1. c. p. 114. 



