1050 NEW YORK STATE MUSEUM 



Width 10 mm, hight 9 mm, thickness 6 mm. [Am. Mus. cat. 

 no. I - 5 /- 3 - ] This compares quite well with a typical 0. 

 n e g 1 e c t a from the Niagaran of Lockport 1 except that the 

 Lockport specimen has only six lateral plications on the pedicle 

 and five on the brachial valve on each side. It differs as widely 

 from the ordinary specimens of C. n e g 1 e c t a as does C. 



hudsonica. 



Rhynchospira excavata sp.nov. 



General form and proportions as in R. f o r m o s a Hall, of 

 the Helderbergian. The present species is however very con- 

 vex in the umbonal region, and the cardinal slopes of both 

 valves strongly excavated, a feature which recalls more nearly 

 Camarotoechia than Rhynchospira. The beak of the pedicle 

 valve is strongly incurved over that of the brachial. The apical 

 portion is broken away in the only specimen known so far. 

 The posterior lateral margins of the pedicle valve have a gentH 

 concave outline to almost the middle of the valve, beyond 

 which they round regularly to the front. In the brachial valve 

 the posterior lateral margins form a nearly straight line. 



A shallow median depres- 

 sion begins at the beak of 

 the pedicle valve and grad- 

 ually widens forward, hav- 

 ing in each stage of growth 

 about twice the width of the 

 spaces between the plications. The bottom of the depression is 

 rounded, becoming flatter toward the front. It is margined on 

 each side by a plication, which is somewhat weaker than those 

 covering the remainder of the shell. The latter are sharply 

 rounded and at intervals appear subnodose in the exfoliated shell, 

 this feature being caused by strong concentric striae. There are 

 in all nine plications on each side of the median line; two of 

 these are very faint and short and occupy the depressed 

 cardinal slopes. In the brachial valve a faint plication marks 

 the center and corresponds to the depression of the pedicle 

 valve. On each side of this are seven plications, the interspace 



1 Palaeontology of New York, v. 2, pi. 57, fig lh, 1, o; Am. Mus. i^. 



Fig. 9 Rhynchospira excavata 



