Weller — Kinderhook Faunal Studies. 441 



acter of the fauna, nearly all of the species recognized being 

 smaller than their close allies in the Hamilton faunas. 



ChONETES GLENPARKENS18, n. Sp. 



Plate 1, Jig. 7. 



Description. Shell rather small, pedicle valve inflated, 

 with small, depressed auriculations towards the cardinal ex- 

 tremities. Surface marked by 28 to 30 rounded costae at the 

 margin, many of which bifurcate at about the middle of the 

 valve. The minute surface markings consist of tine concen- 

 tric costae which are strongest upon the tops of the ribs. 

 Number and character of the cardinal spines not determined. 



The dimensions of a pedicle valve are: length, 6.5 mm.; 

 width, 8 mm.; convexity, 3.5 mm. 



Remarks. This species is closely allied to C. logani of the 

 Kinderhook faunas. It has the same sort of fine concentric 

 markings, but it may be distinguished by its much coarser 

 radiating costae, and by its somewhat greater inflation. 



Besides the species of Chonetes just described, there are 

 two other members of the genus in the Glen Park fauna 

 represented by material too imperfect for identification or de- 

 scription. The first of these (plate 1, fig. 8-12), isthecom- 

 monest of the three species. All the specimens which have 

 been observed were more or less waterworu before being 

 fossilized. The dimensions of an average specimen are: 

 length, 7 mm.; width, 9 mm.: and convexity, 2 mm. The 

 surface is marked by 45 to 50 rounded costae, but the finer 

 surface markings have been destroyed on all the specimens 

 examined. In all the specimens in their present condition, 

 the hinge line is a little shorter than the greatest width of 

 the shell, the cardinal extremities being rounded, but this 

 may be due to their worn condition since the lines of growth 

 meet the hinge-line at nearly right angles. The spines have 

 usually been entirely destroyed, but their eroded bases may 

 occasionally be detected, although it is not possible to deter- 

 mine their number or their direction. These specimens have 

 something of the aspect of C. logani, but this species cannot 

 be certainly recognized without the fine surface markings. 



