Grabau 



— Faunas of the Hamilton Group. 



281 



Genus Atrypa, Dalmari. 



124. Atrypa reticularis, Linne. 



1867, Hall, Pal. N. Y., vol. 4, p. 316, pi. 51, to 53a. 



I have not found this species below the Athyris layer, though above it, 

 in certain layers, it is by no means rare. It is common in the S. demissa bed 

 where the specimens are well preserved. It has not been noticed in the 

 Encrinal limestone, but it occurs again in the lower Moscow shales, and is 

 common in the coral layer, though less so than the following. 



125. Atrypa aspera, Dalman. 

 1867, Hall, Pal. N. Y., vol. 4, p. 322, pi. 53a. 



This species has a much more restricted distribution than the preceding. 

 I have found it only in the lower Moscow shales, where it is the most abun- 

 dant brachiopod of the coral layer. A single specimen was found at a little 

 distance above this. 



The characteristic spines found in most of the specimens from Moscow, N. Y. r 

 are seldom preserved in the Eighteen mile creek specimens, only three crushed 

 specimens from the coral layer preserving any trace of them. The specimens 

 are usually robust and well formed, and otherwise correspond to the speci- 

 mens from the Genesee valley. No signs of wearing are exhibited by the 

 shells, and the loss of spines is possibly to be attributed to maceration in 

 shallow water where little sediment was accumulating, or to slight wave or 

 current action. 



Genus Vitulina, Hall. 



126. Vitulina pustulosa, Hall. 

 1867, Hall, Pal. X. Y., vol. 4, p. 410, pi. 62. 



This species is quite common in the Encrinal limestone, more than tAventy 

 specimens having been obtained. These occur, however, usually as separate 

 valves, both pedicle and brachial, and all are exfoliated, consequently do not 

 show the surface pustules. The specimens are all small, the largest one 

 obtained measuring 12 mm. in height, by 14 mm. m width. I have not 

 observed the species outside of this limestone. 



