47 



The first azygous plate is large, longer than wide, hexagonal, 

 truncates a subradial, and extends as high as the second radial. 

 Beyond this neither the azygous area or the proboscis is pre- 

 served, in our specimen, but there are numerous scattering plates 

 belonging to the proboscis which are transversely serrated. 



This species is so different from all others that have been 

 described that no comparison is necessary with any of them to 

 distinguish it. 



Found by Prof. A. G. Wetherby, in the Kaskaskia Group, in 

 Pulaski county, Kentucky, and now in the collection of Wm. F. E. 

 Gurley. 



ZE^CKINUS PULASKIENSIS, n. Sp. 



Plate 4, Fig. 12, azygous side; Fig. 13, opposite view. 



Species below medium size, subcylindrical, constricted above the 

 calyx, truncated below and slowly tapering at the superior end. 

 Calyx very low, broadly truncated and depressed below. Surface 

 smooth or finely granular. Column very small and round. 



Basals deeply sunken so as to be hidden by the column. Sub- 

 radials longer than wide, and curve into the basal concavity and 

 upward at about the middle part, which is gently rounded, so as 

 to show the superior ends in a side view. First radials about 

 one and a half times as wide as high, pentagonal, truncated the 

 entire width above, and separated from the second plates, which 

 belong to the free arms by a gaping suture. Second plates or 

 first arm plates longer than the first radials, nearly as high as 

 wide, constricted in the middle part, and truncated the entire 

 width above in a line more or less inclined for the support of the 

 second arm plate, which is short and cuneiform. There are, there- 

 fore, only five arms in this species. The arms are robust, sub- 

 fusiform and composed of a single series of short, cuneiform 

 plates. The pinnules are short and strong. 



The first azygous plate is much smaller than the second, and is 

 embraced between a subradial and the first radial on the right, 

 without extending to the second subradial as is usual in this 

 genus. The second azygous plate is longer than wide, truncates 

 a subradial and curves in toward the vault so as to extend very 

 slightly beyond the single first radial on the left. The third 

 azygous plate rests upon the first and curves in upon the vault 

 at the top of the first radial. The fourth azygous plate truncates 



