1886.] PROCEEDINGS OF UNITED STATES NATIOilAL MUSEUM. 21? 



The two forms figured by Leche as Iccvigata and Iwvis certainly exist; 

 but the differences between them are such as ordinarily characterize 

 the sexes in dioecious acephala, and I have always so referred them. 

 Further investigation may be needed to settle this. 



Pecten (Propeamusiuni) alaskeusis Dall ? 



Pecten Hoslyufii Forbes, var. ma;o>- Leche, 1. c, p. 452, 1883. 



Near Bering Island in 75 fathoms, Vega Expedition. 



In a study of the deep-sea pectens of this group, in connection with 

 the PectinidsB of the Blake dredgings, I have determined that the gen- 

 uine Pecten hoskynsi is not an Arctic species ; the shells called Ho.skyihsi 

 h^ Jeffreys and others from Arctic Norway, &c., are P. pustnlosiis Yer- 

 rill, which has no internal ribs; from Alaskan waters and the adjacent 

 Arctic seas the only pecten yet found belonging to this group is the P. 

 alaskeusis Dall (1871), which has many more internal ribs than the At- 

 lantic forms and was pronounced distinct by Jeflieys. It is probable 

 that this is what Dr. Leche refers to, because it is not rare in the region 

 and might be expected to occur there. Still in the absence of figures 

 or specimens I do not feel like expressing a dogmatic opinion in regard 

 to it. 



Placunanomia macroschisma Deshayee. 



Bering Island, Grebnitzki. 



This completes the list of additions and the following table will sum 

 up the total mollusk-fauna, giving at one glance the known species, the 

 collectors, and something of the range of the forms referred to : 



FAUNAL SUMMAKT. 



Species of Commander Islands. 



Gonatus amoenus 



Lestoteuthis fabricii (?) 



Cylicbna propinqua 



/Eolidia papillosa 



Cadliua pacifica 



Acantliodoris pilosa 



Limax (Agriolimas) hyperboreus. 



Vitriua exilis 



Hyalina radiatula 



Counlus fulvus var 



Pat Ilia ruderata var. pauper 



Piipilla decora and arctica 



Liiunaja ovata 



Limiuca humilis 



Sipbouaria thersites 



TracbjTadsia aleutica 



Touicella marmoiea 



Tonicella submarraorea 



Tiachydormon ruber 



Scbizoplax brandtii 



Loptochiton canccllatua 



Placipborella stimpsoni 



Cr.vptiichiton stelleri 



Acnura testudinalis patina 



Acmuia pelta 



Collected bv — 



Ran are. 



(?) 



(?) 



