242 NEW YORK STATE MUSEUM 



Corynoides curtus Lapworth var. comma nov. 



Plate 13, figures 5, 22-24 



Corynoides curtus Ruedemann. N. Y. State Mus. Bui. 42. 1901. p. 526 



Description. Rhabdosome very small (average 4 mm, maximal length 

 5 mm) and relatively wide (.6 mm), attaining its maximal width at half its 

 length, strongly curved so as to frequently describe a quadrant, consisting 

 of a small, inconspicuous sicula (.6 mm), which rarely is preserved, and three 

 thecae. Thecae not diverging from the sicula ; of equal length. Aperture 

 of the sicula plain, those of the thecae straight, normal to the axes of the 

 thecae and provided with one mucro each, that is of the same character and 

 direction as in the typical species. Nema present. 



Position and locality. Very common 

 in the shales, exposed at the power house 

 below Mechanicville. It is there asso- 

 ciated with G 1 o s s o g r. quadrimu- 

 cronatus, D i p 1 o g r . f o 1 i a c e u s, 

 C 1 i m a c o or r . caudatus, and numer- 



145 x 46 



Fig. 145-48 Corynoides curtus var. comma 

 nov. Fig. 115-47 Common aspect of the form. Fig. 148 



A larger specimen, x 7 



ous mollusks indicating a horizon trans- 



itional between the Trenton and Utica formations or lying near the base 

 of the Utica formation 



Remarks. In the above cited publication this form has been referred 

 to C. curtus, but the constancy of its differential characters requires 

 its recognition as a separate variety (or mutation). It differs from the 

 typical curtus by its shorter and at the same time stouter form and its 

 marked curvature, while the diminutive size of the sicula, the curvature and 

 especially the obliquely outward direction of the apertural spines clearly 

 indicate so close a relationship to C . curtus that the ends of taxonomy 

 appear to be served best by retaining this form within the bounds of the 

 typical Utica species of Corynoides. 



