LOWER SILURIC SHALES OF THE MOHAWK VALLEY 63 



111 comparing these faunas with that of the Canajoharie shale, 

 we find that most graptolites of the two formations are but 

 little different. Closer scrutiny shows, however, that the 

 Snake Hill beds contain certain forms which do not appear in 

 the Canajoharie beds. The most important of these are : 

 Climacograptus caudatus, C. scharenbergi, 

 Cryptograptus tricornis mut. insectiformis. 

 On the other hand, Climacograptus mohawkensis 

 and Diplograptus quadrimucronatus mut. 

 cornutus are peculiar to the Canajoharie shale. But also the 

 forms which are common to both, show a marked difference in 

 their frequency. Thus of Dicranograptus nichol- 

 s o n i 1 and Climacograptus spi'niferus 2 which 

 are among the most common graptolites of the Snake Hill beds about 

 Saratoga lake, the former is extremely rare in the Canajoharie beds, 

 and the latter only frequent in the lower portion of the Canajoharie 

 beds, about Hudson Falls and Ballston. On the, other hand, 

 Lasiograptus eucharis is all but absent in the Snake 

 Hill beds, but well established in the parallel belt of Canajoharie 

 beds, and while Corynoides calicularis occurs in both, 

 C . g r a c i 1 i s , which occurs in the Snake Hill beds in several 

 localities, seems to enter only the lower portion of the Canajoharie 

 beds about Hudson Falls. 



Watervliet, N. Y. The species new for this formation collected there 

 are: 



Trematis terminalis Emmons. Large form approaching T. millepunc- 

 tata Hall 



Schizambon fissus var. canadensis Ami, Large, long-spined specimens 



Lingula obtusa Hall 



Cyrtolites trentonensis Conrad. Much flattened specimens 



Carinaropsis cf. carinata Hall. Large specimens . 



1 As we have already noted, this species ranges here even into the 

 Indian Ladder shale. This corresponds to the great range of the species 

 in Europe, where it is cited from the zone of Nemagr. gracilis (cor- 

 responding to our Normanskill shale) in Sweden and reaches into the 

 Hartfell shale in Great Britain. 



2 Climacogr. spiniferus was at first distinguished by us as 

 C. typical is mut. spinifer (title 60, p. 411) to identify a form 

 figured by Hall (title 3, pi. 73, fig. 2a) as coming from Ballston, Saratoga 

 county and which we have found to mark the shales directly overlying 

 the basal Trenton limestone (Glens Falls limestone) at Hudson 

 Falls (Sandy Hill). On account of its stratigraphic importance and apparent 

 constancy of characters for a considerable length of time we prefer to 

 distinguish this type as of specific rank ( C 1 . spiniferus). 



