168 PALAEONTOLOGY OF NEW- YORK. 



Productella hirsata, var. rcctispina. 



PLATE XXIV. 



A group of figures at the lower part of this plate were originally sepa- 

 rated, under the impression that they were a distinct species ; but later 

 examination has induced me to unite them with this as a variety, till 

 more positive differences can be ascertained. They occur in a fine fissile 

 and almost slaty sandstone in the Chemung group in the south part of 

 Steuben county, and a few specimens from other localities have the same 

 characters : these hold a somewhat higher position in the series than 

 those from Philipsburgh. The condition of their preservation in a coarse 

 matrix has given a somewhat different aspect to the surface markings, 

 and the spines on the hinge-line, when preserved, are vertical ; while 

 in the specimens from Philipsburgh and the Blossburgh railroad, the 

 spines are always directed obliquely outwards. The same feature of dis- 

 tortion or inequality on the two sides of the beak prevail in all the spe- 

 cimens from this locality in Steuben county, as well as in those of Alle- 

 gany county and other places. The casts or impressions in this rock 

 have a more coarsely pustulose or wrinkled surface ; and in some imper- 

 fect specimens of the same type from Meadville ( Pennsylvania), the 

 valves have had a diameter of more than two inches, and the surface is 

 strongly wrinkled on and near the cardinal margins. 



A single individual in a semicalcareous matrix from Troup's creek near the 

 Pennsylvania lino, in the vicinity of the sandstone specimens, preserves the sur- 

 face characters in greater perfection than any specimen elsewhere observed. An 

 enlarged view of a portion of this shell is given in one of the figures. 



