﻿CRTSTARIA 227 



line of the shell being nearly straight ; growth lines irregular, 

 becoming almost snlcate on the border of the shell ; epidermis 

 dark chestnut or blackish, shining in the middle of the disk ; 

 hinge line arched ; there is a short curved lateral in each valve; 

 pseudocardinals wanting or indicated by a mere raised line ; 

 escutcheon square ; beak cavities shallow, with a few deep 

 pits ; anterior muscle scars irregular ; posterior scars some- 

 what crescentic, their upper points reaching to the posterior 

 ends of the laterals ; nacre bluish-white, milky. 



Length 140. height 100, diam. 60 mm. 



Cambodia. 

 Anodonta hcUiio Morelet, Rev. et Mag. Zool., XVIII, 1866, 



p. 167. 

 Cristaria hellna Simpson, Syn., 1900, p. 584. 



Compared with C. plicata, this si)ecies is more rhomboid, 

 more inflated, and drawn out behind into a more decided point, 

 this point being nearer the base line than in pUcata, and its 

 epidermis is more chestnut and not so much olive-colored. Its 

 nacre is milky-white, that of plicato is not. The above descrip- 

 tion is from a specimen in the writer's collection, which came 

 from Cambodia. Morelet's specimens are larger, his type be- 

 ing 173 millimeters in length. 



Cristaria herculea ( Middendorff). 



Shell irregularly ovate, somewhat solid, inflated, with a very 

 high, rounded or somewhat biangulate posterior ridge; beaks 

 low but full, scul]:'tured with a number of wide, low ridges 

 running nearly parallel with the hinge line and extending 

 well out on the shell ; on the posterior slope there is a row of 

 plications extending from the beaks towards the posterior end 

 and below these folds there is a low, radial ridge ; growth 

 lines irregular ; epidermis blackish on the body of the shell 

 where it is developed into concentric lamellae or ridges, and 

 smooth and brownish on the earlier growth. There is a very 

 feeble anterior wing and a low dorsal one : pseudocardinals 

 wanting or represented by a mere raised line ; laterals, one in 



