12S KANSAS UXIVERSITT QUARTERLY. 



ealcite dming the process of fossilization. The species seems very 

 closely allied to the northern European form. Astarte duhoisiana 



d'Orb. 



tinnioinya inontanaenfis Meek. Plate XXVI. fig. 1. 



'^ nsr-areaate in general outline, convexity regular ; hinge 



V straight, extending from the beak posteriorly by 

 .- .riigth. The beaks are prominent and raised above the 

 r. The dorsal border is broadly rounded. The posterior 

 margin forms an obtuse angle, with its apex near the median line of 

 the border : the anterior margin is rounded. The umbonal region of 

 the shell is ^"*^ slisrbtly cci:;vex. nearly flat. The surface of the shell 

 exte - . le of the jKDSterior margin forms 



a ra::ie: carr-,: arc::. The surface ornamentation con- 



sists of _ : winded ridges, which in passing back from the 



beak form in : nal regi irangular figures: then for 



about one-th' - r dorsal slopes the quadrangular 



figures are - - nes which have an acute angle 



on the c - ^ ^ These in turn are replaced by figures with the 

 dorsal ang r .^;— ing more and more obtuse, until near the dorsal 

 b?rd-r the figures become almost elliptical in form. The surface is 

 -ked by finer concentric lines of growth, 

 i-' " -nsions! Length. 5^3 mm.: width, 23 mm.: height, ^ mm. 

 Cxeolc^cal horiz'Dn : The species occurs in the arenaceous nodules 

 of Xo. 13 of the section, where it is associated with Belemnites densus, 

 ■ ^i. Pinna Jilngi, Pxeudomonotis curta, Pleuromya 



-:c. It is also reported, as stated below, from the 

 Yellowstone canon, Montana. 



Eemarks: The typ^ spe ' is species was described by 



Meek in the Unite! States _ . Reports for 1^72. Its deter- 



mination was based upon an imperfect specimen, and from the figure 

 and description it is dLScult to say whether or not the Wyoming 

 species is the same. It is placed here, however, provisionally. 



The species is also very closely allied to the European species, 

 ' ' lenst., described from the Jurassic fauna of Kussia 



^ : iins. S: ;1 =- is its connection that it maybe 



merely a variety of the Eur -cies. 



fronioiuyn sj.. Plate XXVI, fig. 2. 



Tie cast of a shell which appears to belong to a different .?i)ecie5 

 was ii/und associated with Goniomya mjonianaensis. It appeare from 

 the cast that it is a much narrower and proportionally longer shell 

 than the latter. These- _ :her characteristics pres- 



ent are analogous to tho>- .: .- . - . . • -_^_-i species. 



