ACANTHOPLEURA. 229 



The identity of C. magellanicus Gm. and Chemn. with the West 

 Indian species, although extremely probable, cannot be regarded as 

 absolutely established. At all events the name is hardly acceptable, 

 for no Acanthopleura of this type has been collected at or near the 

 Strait of Magellan. Rochebrune's citation (Moll. Cap Horn) is 

 worthless, on account of his ignorance of generic and specific charac- 

 ters in this group, and his false synonymy in the case of this species. 

 Gmelin's C. granulatus, the next name in order of priority, was 

 founded upon specimens from St. Thomas excellently described and 

 figured by Chemnitz. The identity of the next form described 

 by Gmeliu, piceus, is also moderately sure. Reeve's C. occidentalis 

 (see pi. 50, fig. 42) is an ordinary form of granulatus. 



Shuttleworth has described two West Indian Acanthopleuras of 

 which I have not seen authentic examples. His descriptions here 

 follow : 



C. {Acanthopleura) mucronulatus. Shell oblong-ovate, elevated, 

 narrowed in front, black-brown, unicolored ; valves all over very 

 minutely concentrically punctate-striate, carinated dorsally, pro- 

 duced backward in a short apex ; lateral areas slightly elevated. 

 Girdle spotted with white, having scattered very minute, sand-like 

 grains. Length 9, breadth 6 mill. Porto Rico, Blauner ! Described 

 from a single specimen ; distinguished from the young of granulata 

 by the form and especially the very minutely sanded girdle. Shell 

 inside dull whitish, slightly greenish. 



This may prove to belong to some other group. C. {Acantho- 

 pleura) blauneri Shuttl. was founded on a single black-brown spec- 

 imen from Porto Rico, having unicolored black girdle densely 

 clothed with very minute spines, more minute than in piceus, from 

 which blauneri also differs in being more depressed and more 

 minutely sculptured. Length 52, breadth 32 mill. I do not see 

 that this falls outside of the well understood range of variation of 

 A. granulata. 



The following unfigured form may prove to be a distinct species if 

 the locality be confirmed. 



Chiton (Acanthopleura) piceolus Shuttl. Shell ovate, wider 

 behind ; obscure olivaceous, maculated with black at the middle of 

 the back and at the sides; valves all densely and minutely pus- 

 tulose-granulate ; areas entirely obsolete. Girdle minutely and very 

 densely sandy-spin ulose, alternately maculeated brown and white. 

 Length 10, breadth 6 mill. (Shuttl. Bern. Mittheil. 1853, p. 82.) 



Tenerife, Canaries, (Blauner) ; rather common. 



