Il6 NEW YORK STATE MUSEUM 



i 



with the difference, however, that the sculpture is much finer in the 

 shale variety, the ridges and bars being just about twice as closely 

 set and correspondingly lower ,than in the trentonensis (15 

 to 1/ ridges in 5 mm as against 6 to 9 in C. trentonensis). 

 This difference having been found to be constant in all specimens 

 observed in the shale (Snake Hill beds at Watervliet and the 

 Schenectady beds at Schenectady and Schoharie Junction), it 

 becomes necessary to recognize it as of at least varietal importance. 

 We therefore propose to distinguish this form as var. multi- 

 cos t a . 



It represents the other extreme of variation to the type described 

 by Emmons (Amer. Geology, i :2o8) as C. hudsonia from 

 the Lorraine beds at Lorraine, N. Y., which latter form exhibits the 

 trentonensis-sculpture about twice as coarse as the Trenton type. 



A fragment of a specimen from Watervliet retains part of the 

 apertural lobe. The sculpture on this consists of the transverse 

 ridges which are much more crowded than on the lateral faces of 

 the shell and sharply bent forward in the middle. 



Eoharpes ottawensis (Billings) 

 PI. 9, fig. I 



A single specimen found in a loose slab of Snake Hill shale on 

 Snake hill, represents thus far this Canadian species in our State. 

 The species was first described from the Trenton limestone of 

 Ottawa (Can. Pal. Fossils, 1865, i :i82) ; later a doublure of a head 

 shield from the Galena of Wykoff, Minnesota, was also referred 

 with doubt to this species by Doctor Clarke (title 32, page 757)- 

 Weller (title 53, page 191) has also recognized the species in the 

 fauna from the Jacksonburg limestone at Jacksonburg, N. J., and 

 Bassler (title 62, page 11 1) lists it from the Liberty Hall limestone 

 (Chazy) of Virginia. 



Our specimen has been slightly laterally compressed and there- 

 fore appears somewhat more slender than the type, but otherwise 

 it fully agrees with the original drawing of the latter. It also dis- 

 tinctly exhibits the surface punctae characteristic of Billings's 

 species. 



Isotelus gigas DeKay 



PL 10, fig. I 



We figure here a fairly well-preserved specimen of this widely 

 known trilobite which, labeled as coming from the bluestone 

 quarries at Rexford Flats, N. Y., has been in the State Museum 



