150 



3Iodwlopsis Versaillesensis. 



an extensive ran^e, but it is very rare to find anything more than a 

 niere cast. It is found quite common from 300 feet above low water- 

 mark to the rocks of the Upper Silurian, and is rarely found below 300 

 feet above low water-mark. 



3fodiolo2ms Versaillesensis— (^8. A. Miller). 



Fig. 18 — Modiolopsis Versaillesensis. 



Fig. 19 — Modiolopsis Versaillesensis. Hinge 

 line and muscular impression. 



Equivalve, inequilateral, oblong, expanded and compressed poster- 

 iorly ; basal margin contracted or arched upward, below the beaks ; 

 cardinal line straight ; beaks near the anterior extremity, and slightly 

 more prominent than those of the Modiolopsis modiolaris ; umbones sub- 

 angular and extending obliquely, posteriorly ; surface marked by con- 

 centric lines ; muscular imi^ression circular and deep, below and anter- 

 ior to the beak ; mesial ridge between it and the umbonal cavity ; 

 hinge line plain and smooth, except a slight ligamental depression 

 below the beak. 



Length of specimens examined varying from f inch to 2i inches ; 

 breadth and thickness in proportion to length. 



This species differs from the Modiolopsis modiolaris, in having a more 

 prominent beak, more angular umbones, different hinge line, and lig- 

 amentary attachments, and in having the muscular impression farther 

 anterior to the beak. Casts of the two species might not be distin- 

 guishable from each other. 



This species was found Iw me at Versailles, Indiana, about 300 feet 

 below the rocks of the Upper Silurian, and associated with Anomalo- 

 donta gigantea, Anodoiitopsis (?) Milleri, Pleurotomaria troindoplxeva, Tel- 

 linomya occidentalis, etc. 



