PROCEEDINGS 



OF THE 



UNITED STATES NATIONAL MUSEUM. 



1878. 



I>ESCRII»TIOIVS OF KE^V FORITIS OF MOI.r.USK» FROITS ALASKA 

 CONTAIIVED IIV THE COIiLECTIOlVS OF THE IVAXIONAI^ 



MSJSEUiyi, 



By "W. H. UAL.L.. 



CHITONIDJE. 

 Genus AMICULA Gray. 



Type A, vestiia Sowerby. 



Subgenus Chlamydochiton Dall. 

 Ch. t. ^Amiculce^ similiter sed branchiae ambientes. 



Type Chiton amiculatua Pallas. 

 Amicula proper bas the branchiae median. 



Genus LEPTOOHITON Gray. 



Leptochiton Belknapi Dall, n. s. 



L. t. elongata,, valdeelevata,dorsualiter angulata; albidaplusminusve 

 cinereo et nigro tincta; valvis elevatis, apicibus distinctis ; mucrone 

 centrali couspicuo; sculptura ut in L. alveolo, sed granulis in areis dor- 

 sualis sparsim et quincuucialiter dispositis; valva postica sub apice con- 

 cava, postice sinuata; zona minima spiculis tenuibus versus marginem 

 munita. Lou. 10, lat. 3™™. Div. 90°. 



^a&.— North Pacific Ocean, in lat. 53° 08' K, and Ion. 171° 19' W., 

 at a depth of 1006 fathoms, black sand and shells. Brought up in the 

 sounding-cup, on the sounding expedition of the United States ship 

 Tuscarora, Capt. George E. Belknap, TJ. S. N., in 1874. 



This specimen comes from a greater depth than any specimen of the 

 order hitherto collected. It is nearest to L. alveolus Sars, from the coast 

 of Norway. 



Genus TEACHYDERMON Cpr. 



Subgenus Traohyeadsia Cpr. (Ms.). 



Trachydermon, valvis centralibus bi- seu pluri-fissatis. 

 Type Chiton fiilgeirum Reeve. 

 Trachyradsia aleutica Dall, n. s. 

 T. t.parva, rufo-cinereii, oblonga, fornicata; jugo .icutissimO; mucrone 

 Proc. Nat. Mus. 78 1 I 



