ACANTHOPLEURA. 223 



incana of Australia and the so-called Acanthopleuras of Japan, 

 which are characterized by a flat crescentic callus in place of the 

 teeth in the tail- valve (pi. 53, fig. 35). 



The variation of this species is great, and a number of subspecific 

 or varietal forms will probably be distinguished eventually. My 

 material is not extensive enough to permit me to diagnose these, or 

 to indicate their areas of distribution ; and I therefore offer below 

 the original descriptions of the several described forms. 



Typical SPINIGER is characterized by the possession of longer 

 spines than any of the other forms. It is thus described by 

 Sowerby : 



C. spiniger Sowb. (pi. 48, fig. 22). Shell depressed, ovate-elong- 

 ated, all over granulated ; valves reclining, ends rounded ; girdle 

 wide, furnished with numerous subarcuate spines. .Length 2*1, 



width 1'5 inch. Habitat ? Mus. Stainforth. Another spini- 



ferous species, rather narroAV in proportion to its length ; depressed 

 and finely granulated ; the valves are rounded at the lateral extrem- 

 ities, with their apices leaning backward, and their lateral areas 

 scarcely distinguished ; numerous slightly curved spines, nearly one- 

 half an inch long, cover the margin ; general color like a faded leaf, 

 with dark patches of reddish-brown covering the lateral and part of 

 the central areas of some of the valves, and a dark dorsal band 

 bordered by bright green and white (Sowb. in Mag. Nat. Hist.) 



The fig. 22 is a copy of the original one published in Mag. Nat. 

 Hist., and fig. 23 of that in the Conchological Illustrations, which 

 probably represents the same specimen. Note the length of the 

 girdle-spines. 



Reeve's figure (pi. 48, fig. 27) represents a larger specimen, 

 collected by Cuming in the Philippines. In this the spines are 

 much shorter. Figs. 24-26, pi. 48, represent valves from a specimen 

 very similar in all respects to Reeve's figure (see pi. 48, fig. 27). 

 The granulation is rather obscure, or transformed into low wrinkles. 

 The spines on the very wide girdle are both long and short (1-11 

 mill.) 



Figs. 31, 32, pi. 48, are drawn from a specimen from the Viti Is. 

 collected by Andrew Garrett. In this specimen the dorsal ridge has 

 a blackish -green band with a wider fleshy-white triangle on each 

 side of it, and a streak of green, the rest of the surface of the valves 

 being black except the large ashy-eroded patch on each side of the 

 black (eroded) beaks. The central areas have some scattered gran- 



