LOWER SILURIC SHALES OF THE MOHAWK VALLEY 1 15 



4 The first siphonal funnel was collarlike reflexed and thus 

 formed the scar (Barrande's " cicatrix "). This first siphonal funnel 

 has as a rule a different shape from that of the other funnels of 

 the conch. 



Our material consisted only of about half a dozen protoconchs 

 which, however, were large enough (1.6 mm wide) to be broken 

 out and in two instances made into thin sections. Both the exterior 

 view and the sections verify Pocta's observations as to the width of 

 the protoconch being greater than the first camera and the reflexed 

 character of the first funnel. It will be noticed that in O . h u d - 

 s o n i c u m the volume of the protoconch corresponds approxi- 

 mately to that of the first camera. 



This is the first observation of the protoconch of an Orthoceras 

 in the Lower Siluric, Doctor Clarke's specimen coming from the 

 Devonic and Professor Pocta's from the Upper Siluric. The 

 different character of the nepionic conch of Endoceras has already 

 been described by Holm in 1885 (Pal. Abh. von Dames and Kayser, 

 volume 3, and Geol. Foren. i Stockholm Forhandl. 1896, volume 18). 

 The protoconchs of orthoceratites are by no means rare in the Utica 

 shale, for we had already obtained a large series of pyritized speci- 

 meni: at Dolgeville some fifteen years ago. These, however, were 

 lost in transportation and the bed has become inaccessible by the 

 building of a dam. The Dolgeville material was the same or a very 

 closely related species. 



Oncoceras (?) sp. 



PI. 8, fig. 12 



A completely flattened specimen from the Canajoharie shale at 

 North Albany. Its condition does not allow either a definite generic 

 determination or a sufficient specific diagnosis. The living chamber 

 was short and the apertural portion somewhat contracted; the 

 aperture apparently regular and circular. The septa are seen only 

 faintly, they were closely arranged and arched on both the ventral 

 and dorsal sides. The siphuncle is very indistinct, apparently with 

 straight segments. The form seems to be distinct from the other 

 Trenton species of Oncoceras but would not warrant being named. 



Conularia trentonensis var. multicosta nov. 



Both the Schenectady and the Snake Hill beds have furnished 

 specimens of a Conularia which possesses the characteristic apical 

 angle (18 20) and sculpture of C. trentonensis, i. e. a 

 system of transverse ridges crossed by closely set longitudinal bars, 



