. 180 



all compressed, and it shows the peculiar form which clearly distin- 

 guishes it from M. bellacincta. 



In the shaly portion of the Trenton limestone, near Lowville, Lewis- 

 county. (State Collection.) 



.. SUBULITES ABBREVIATA, (n. species.) 

 Plate 3, fig. 2, a, b, c. 



Short, suhfusiform, last volution making nearly the whole bulk of the 

 shell ; spire rapidly diminishing ; composed of about three volutions j 

 aperture long, very narrow above ; outer lip straight and parallel to the 

 axis of the shell ; margin of the shell opposite the outer lip, and with 

 the spire above forming a regular curve from apex to base. 



This species possesses the character of the genus as expressed in the 

 S. elongata, but it is extremely different from that one in the short spire 

 and curved outline of the back of the shell. The specimens are inte- 

 resting as presenting a second species of dt peculiar genus, and one not 

 recognized above the lower silurian period. # 



The specimens figured were obtained from the semicrystalline lime- 

 stone in the higher part of the Trenton limestone, near Watertown, 

 Jefferson county. The position and associated fossils are the same as 

 in the other species of the genus. (State Collection.) 



' ONCOCERAS CONSTRICTUM. 

 Plate 3, fig. 3. 



Reference. — Page, 197, plate 41, figs.- 6 and 7, Palaeontology of New- 

 York, vol. 1. 



This species was described from fragments and the characters were 

 not completely defined. The specimen figured is almost entirely per- 

 fect, showing the contracted, nearly circular aperture, and the swelling 

 above, which presents a transversely oval section, suddenly tapering 

 from thence towards the apex, which is curved from the commencement 

 of the contraction ; surface finely striated, with the striae arching up- 

 ward along the dorsal line. 



This specimen is almost entire, a small portion of the apex having 

 been broken off only. It is one of the most remarkable forms of 

 cephalopoda in the lower strata. The specimens figured in the first 

 volume of the Palaeontology of New- York, are such as are usually 

 found, the one now described being the only perfect one known to me. 



From the limestone in the neighborhood of Trenton Falls. 



