34 CH^ETOPLEURA. 



To this species Carpenter unites C. scabriculus Sowb. (pi. 12, figs. 

 55, 56) and Ischnochiton parallelus Cpr., a figureof which, drawn from 

 a Carpenterian specimen from Cape St. Lucas, is given on pi. 12, 

 fig. 50. It is likely that C. columbiensis should be added to the 

 synonymy, as it presents no differential characters of much value. 



Var. PARALLELA Cpr. PI. 12, fig. 50. 



The specimen before me of the form parallelus, measures 17 by 

 11 mill. It is rather acutely carinated, the sides slopes nearly 

 straight. There are 17 beaded longitudinal threads on each side 

 of the central areas, and from 6 to 7 rows of separated, rounded ^ 

 erect tubercles on each lateral area. The lateral areas are decid- 

 dly elevated; the mucro is slightly prominent. The girdle has 

 sparsely scattered hyaline short hairs. The gills continue as far as 

 the front end of the foot. The outside is reddish, marbled with 

 darker and white, the girdle dark ashen. The interior is bluish- 

 white. 



Cape St. Lucas. 



The style of sculpture is the same as in C. gemmea, but the shell 

 is much broader than in that species. 



Var. PRASINATA Cpr. 



Similar to parallela, but vivid green ; lateral areas irregularly 

 ornamented with series of tubercles. Cape St. Lucas. 



Var. COLUMBIENSIS Sowerby. PL 12, figs. 51, 52. 



Shell ovate, a little depressed, ashen ; end valves and lateral 

 areas sparsely granulose ; central areas longitudinally granose-lin- 

 eate. (/%.) Length 31, breadth 18 mill. 



Bay of Panama, under stones at low water. 



C. columbiensis SOWB., P. Z. S. 1832, p. 58 ; Conch. Illustr. f. 15. 

 REEVE, Conch. Icon. f. 82. Chcetopleura columbiensis Sby. CPR., 

 ms. 



Carpenter says: Mucro slightly in front of the middle, sub- 

 planate, the posterior part excurved. Interior: posterior valve 

 with 8, anterior valve 9, central 1 slit. Teeth obtuse, scarcely 

 roughened; eaves large; sinus narrow, moderately deep. Girdle 

 leathery, with a few corneous hairlets. . . . One of Colonel 

 Jewett's specimens is of a uniform dark chocolate color, but parts 

 of some of the valves are of a variegated olive. 



Of another specimen Cpr. writes : One specimen of the scabri- 

 culus type. Girdle finely hairy. Red, with dark girdle. On each 



