Weller — Kinderhook Faunal Studies. 159 



Remarks. The individual here illustrated is the most 

 perfect one of the five type specimens in the University of 

 Michigan collection, but it is somewhat smaller than the one 

 whose dimensions are given by Winchell. The author of the 

 species included in it as a variety, a shell from the 

 Chonopectus sandstone below, which, however, proves 

 to be specifically distinct, being the same species 

 for which Hall proposed the name Spirifer extenualus. 

 The differences between the two species have already been 

 noted in the description of the Chonopectus sandstone fauna.* 

 The median septum mentioned by Winchell in his description 

 is scarcely worthy of being mentioned as such, it being noth- 

 ing more than a very slight ridge dividing the two lobes of the 

 diductor muscular impressions. In none of the type speci- 

 mens could the punctate shell structure of this genus be dis- 

 tinguished. The presence of a canaliferous plate is exhibited 

 in one internal cast included among the types, which may 

 have been collected from some other bed. 



III. THE FAUNA OF BED NO. 5. 

 MOLLUSCOIDEA. 



BRACHIOPODA. 

 Leptaena rhomboidalis (Wilck.). 



PI. XIV. f. 19-20. 



This cosmopolitan species has not been observed below this 

 horizon in the Kinderhook section at Burlington. The speci- 

 mens need no comment, they being similar to those occurring 

 elsewhere. 



Orthothetes inaequalis (Hall). 



PI. XIV. f. 16-18. 



Original description. " Shell subplano-convex or de- 

 pressed hemispherical, semi-elliptical in outline ; hinge line 

 equalling the greatest width of the shell. Brachial valve 

 very gibbous, greatest convexity near the center ; umbo promi- 



* Trans. Ac. Sci. St. Louis. 10:77. 



