172 



[Senate 



ted that the true form is scarcely to be determined. The specimen 

 now figured is the most perfect one that has fallen under my observa- 

 tion and will serve to give a better idea of the form and proportions of 

 the species tlian those heretofore given. It preserves five volutions, 

 two volutions of the apex are broken off. The specimen is scarcely at 

 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, 6, c. 



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

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

 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. elo?igata, but it is extremely different from that one in the short 

 spire and curved outline of the back of the shell. The specimens are 

 interesting as presenting a second species of a 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 oS' only. It is one of the most remarkable forms of 



