115 



Sculpture. Owing to the coarseness of the matrix, and the corrosion of 

 the surface in the examples known, the ornamentation is very imperfectly 

 preserved. Some examples show obscurely a fine concentric ridging ; 

 these ridges are much more numerous than those of Lingulella lonyovalis 

 of the Lower Etcheminian Fauna which this somewhat resembles n form. 



Size. Length of the ventral valves 84 mm. ; width 5^ mm ; the 

 dorsal is about 1 mm. shorter. 



Horizon and locality. Sandy gray shales of Assise E. 3 /. at Gillis- 

 Tndian brook. 



The following table will show the size and variation in form of a 

 number of valves : 



VALVES of Var. Leptobolus collis in Assise E. 3/. 



Leptobolus 

 collicia-collis. 



*The distance of each main 

 median line, is recorded in this and 

 8 C. R. 



cicatrice or resting stage, from the umbo, on the 

 the following tables. 



