320 PALEONTOLOGY OF OHIO. 



margin gently arcuate from end to end, and terminating behind in a 

 pointed projection that extends a little farther backward than the lower 

 margin, and curves distinctly downward; posterior margin truncated 

 obliquely from above forward and downward, andvery deeply sinuous, the 

 sinus being directed a little upward and forward; basal margin most prom- 

 inent near the middle, and behind this straight, or sometimes very faintly 

 sinuous, and ascending to the rather obtusely pointed, posterior basal 

 extremity, while from near the middle forward it ascends gradually, at 

 first, with slight convexity of outline, and farther forward with a stronger 

 upward curve until it intersects the dorsal margin above. Surface with 

 an obscure, linear, sometimes minutely crenate carina, or raised line 

 along near, but not exactly parallel, to the lower margin (being most 

 remote from it along near the middle), and another similar but more dis- 

 tinctly crenate carina, running along parallel to and about one fifth the 

 height of the valves below the dorsal margin, otherwise appearing to the 

 unassisted eye as if perfectly smooth, but when examined in a favorable 

 light, by the aid of the highest power that can be conveniently used as 

 a hand magnifier, seen to be very beautifully and minutely striated, the 

 striae being very regular, closely arranged, and more or less divaricating 

 from the carinse. 



Length of carapace valves, 1.25 inches; height, 0.46 inch; convexity 

 of each valve, 0.09 inch. 



This species may be readily distinguished from the last, not only by 

 its smaller size, but by its narrower form and two minutely crenate 

 longitudinal carinae, but particularly by the different nature of its mi- 

 croscopical sculpturing, that of the last described species presenting a 

 delicate reticulated appearance, instead of minute hair lines. The basal 

 margins of its valves, below the carina, are also only a little deflected 

 inward and downward, while in all the specimens of the last yet seen, 

 they are abruptly deflected at an acute angle inward and upward. 



Locality and position : Same as last. 



Sub-genus SOLENOCARIS, Meek, 1872. 



(Proceed. Acad. Nat Sci., Philad., XXIV, 335.) 



I did not submit this form to Prof. Dana, but as it difiers quite as 

 materially (though in other respects) from the typical forms of Ceratiocaris 

 as those I sent to him do, and as widely, or even more widely, from those 

 I sent than the latter do from Ceratiocaris proper, I have ventured to 

 separate it under a distinct subgeneric name. Like the last described 



