Io6o CRANDIDIERTA 



Crandidicria bourguignati Jouhert in Bourguignat, Icon. Moll. 



Tan., 1888, p. 43, pi. XIX, figs. 7-9. — Simpson, Syn., 1900, p. 



829. — Germain, Moll. I,ac. Tang., 1908, p. 683, figs. 35-36. 



A remarkably fomied shell, having a long, biangulate pos- 

 terior beak that curves downward in a striking manner. I 

 cannot feel sure as to the validity of several of these species, 

 as I have seen but a small amount of material belonging to 

 only a few of them. I cannot help suspicioning that in some 

 cases distorted or unhealthy shells have been selected and 

 made the types of so-called species. 



Germain (1. c), considers bourguignati as synonym of gir- 

 audi. He, however, also refers the form to gravida as "a. var, 

 elongata of the rostrata type." 



Grandidieria tsadianus von Martens. 



"Shell solid, oblong-elliptical, much inflated, concentrically 

 striate and marked with more distinct lines of growth ; yellow- 

 ish or greenish-brown ; shortly rounded in front ; subrostrate 

 behind ; dorsal margin sloping in front, horizontal and straight 

 to the end of the laterals, thence oblic^ue at an obtuse angle ; 

 ventral margin strongly curved at both ends ; beaks swollen, 

 incurved, eroded, sculptured with a few, scattered nodules and 

 posteriori}' v.'ith a few, short, compressed folds straight or 

 slightly converging. Nacre bluish, somewhat shining, slight- 

 ly radiate striate. Pseudocardinals in the right valve two, 

 compressed, separated by a deep, longitudinal groove, the up- 

 per thin and longer, the lower a little thicker, shorter, less 

 prominent ; in the left valve one, compressed, slightly concave 

 above, prominent and elongated, and one under the beak, com- 

 pressed, triangular, obtuse, with two small, auxiliary teeth 

 between them ; laterals elongate, slightly curved, in the right 

 valve one, sculptured above with two, light, longitudinal lines ; 

 in the left valve two, subequal. 



Length 31, greatest height 20, at the umibones 19, diam.. 

 18 mm. Beaks situated at 1-4 of the length." (von Martens). 



Type locality. South shore of Lake Tsad. 



