BEEKM AN TOW N AND CHAZY FORMATIONS OF CHAM PLAIN BASIN 427 



with darker material, which is termed by Barrande the siphuncle 

 of the specimen, is probably the elongate endosiphocone. The outer 

 and older endosiphosheaths which filled the siphuncle are distinctly 

 shown in the transverse section of the fragment figured by Barrande. 



A specially interesting feature of the specimen is to be seen in the 

 fact that the impressions of the septal necks, which show the char- 

 acteristic forward angulation on the side of the siphuncle nearest 

 to the outer wall of the conch, extend to the tip of the siphuncle, 

 thereby indicating that the nepionic bulb had been completely incor- 

 porated into the phragmocone. This condition is found in the sub- 

 genus Suecoceras of Endoceras and Holm has therefore cited 

 Endoceras marcoui as belonging to his subgenus. We 

 refrain from describing the fragment, since all its characters and 

 dimensions are fully shown by the drawings. 



Genus nanno Clarke 

 Nanno noveboracum sp. nov. 



Plate g, figure 6, 7 



Our collection contains a single specimen which demonstrates the 

 presence of the remarkable and much discussed genus Nanno in the 

 Chazy beds of New York. This is the apical portion of a conch. 

 It exhibits the characteristic preseptal cone or nepionic bulb of this 

 genus, which while in the whole representing a rapidly expanding 

 cone, is asymmetric in such a fashion, that viewed from the siphonal 

 or antisiphonal sides it appears as a symmetric cone [see fig. 6], 

 having a length of 19 mm and expanding from 3 mm at the rounded 

 truncate apex to a width of 13 mm at the beginning of the first 

 cameras; while viewed laterally, it is asymmetric, the piofile of the 

 siphonal side (marked by the contact of the siphuncle and outer 

 wall of conch) being straight, with a geniculation at the beginning 

 of the third camera, and the antisiphonal wall diverging from the 

 siphonal under an angle of nearly 20 to a point 21 mm from the 

 apex, where a sudden contraction takes place, to the middle 

 of the phragmocone, which measures 8 mm in dorsoventral direc- 

 tion. The nepionic bulb is solidly filled with a gray crystalline 

 calcite showing traces of endosiphosheaths. A small subcircular 

 cicatrix or aperture with slightly raised margin is situated upon the 

 middle of the apex, wherefrom radiate a few obscure impressed 

 lines. Of the phragmocone only a short portion of six chambers is 

 retained upon the specimen. The phragmocone is subcircular in 

 section ; its ventral side is distinctly flattened. The cameras are 



