1886.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 211 



Island off the Chilian coast. The P. imporcata and sinuata of Carpen- 

 ter (1865) appear to differ from the others in the fine, close granular 

 scales covering the girdle, and should form a section by themselves, 

 characterized by that character, hy the narrower and higher valves 

 and less patulous anterior extension of the girdle, apparently from the 

 dried specimens not papillose below j as well as a pronounced sculpture, 

 absent from all of the velata type. The latter have broader, flatter 

 valves, an enormous anterior extension of the girdle, studded with pa- 

 pillae below and long tubular mail-clad but flexible spines above, and a 

 series of the latter one opposite each end of each suture in a distinct 

 pore. The girdle, except for these spines, is naked, and on the valves, 

 except for rude ridges of growth and obsolete sutural ridges, there is 

 no pronounced sculpture. For the group typified by F. Blainvillii the 

 name PlacipJiorella must be retained, for the P. sinvata group I would 

 propose the name Osteochiton. As to the species of the PlaciphoreUa 

 group, when the two incongruous forms are eliminated, we have the P. 

 Blainvillii, which differs from the northern forms, according to Dr. 

 Carpenter, by a fewer number of slits in the anterior valve, the P. 

 stimpsoni of Gould, above mentioned, and the P. velata of Carpenter. 

 These two are very similar and may require consolidatiou when a sufiEi- 

 cieut series of both can be obtained for comparison. 



Leptochiton cancellatus Soweiby. 



Chiton cancellatus Sby., Conch. 111., f. 104-5, 1839. 

 Bering Island, Grebnitzki. Alaska, not north of the Aleutians, Dull; 

 British seas, Norway, &c. 



Acmaea testudiualis patina (Eschscholtz) Dall. 



A. testudinalis (L.), var. patina Dall, Sci. Res. Expl. Alaska, p. 122, Dec, 1878. 



Bering Island, Grebnitzki; and Vega Expedition, Aurivillius. 



These specimens are nearer the typical patina than to the typical 

 testudinalis. 



Acmaea pelta Eschscholtz. 

 Bering Island, Grebnitzki. 



Velutina cryptospira Middendorff. 

 Bering Island, Grebnitzki. 



Litorina sitkana Philippi. 



L.tenebrosa Mont., var. costulata (Midd.), Aurivillius, Vega Expl., IV, 325, pi. 

 12, fig. 6, 1885. 



Bering Island, Vega Expedition. 



Litorina sitkana, var. atkana, Dall. 



L. tenebrosa Mont., var. ohtusaicea (Midd.), Aurivillius, Vega Exp., 1. c, p. 325,^ 

 pi. 12, figs. 4, 5, 1885. 



Bering Island, Aurivillius. 



