Raymond : Bkachiopoda and Ostracoda of thf Chazy. 225 



Description. 



Shell transversely oval in outline, nearly straight in front, and 

 rounded at the sides and at the beaks. There are ten to fifteen strong, 

 simple plications, three of which are in the sinus and fdiir on the fold. 

 The sinus is deep and angular, occup>ing about one-third the width 

 of the front of the shell. The ventral beak is acute, not far extended, 

 a little incur\ed. The deliidial plates cover a part of the delthyriuni 

 in a few specimens, but usually they are not preserved. Ordinarily 

 the vahes show only slight traces of surface markings, but well pre- 

 served shells show strong zigzag lines of surface. 



Locality. — This shell is common at the Mingan Islands, St. Martin 

 Junction, near Montreal, and at .Xylmer, Canada. 



8. CamarotcBchia pristina Raymond. 



(Plate XXXIV, figures i-io.) 

 Camaroloechia pristina R.wmond, 1905. American Journal of Science, series 4, 

 Vol. XX, p. 368. 



Description. 



Shell small, transversely oval to sub-circular in outline. Both 

 valves moderately and regularly convex. The dorsal valve has a 

 low^ fold and the ventral vahe a shallow sinus, which is noticeable 

 only toward the front of the shell. There are ten to fourteen strong 

 rounded plications, four of which are on the fold and three in the sinus. 

 The two plications in the middle of the fold are smaller than the two 

 outside ones, and the median jilication in the sinus is the weakest one 

 on the ventral valve. 



The life-history of this species is not very different from that of 

 the species just described, but it should be noted that the middle 

 plications of the dorsal valve, instead of originating at the same time 

 as the others, are intercalated considerably later. This explains 

 why they are weaker than the two just outside them. 



A specimen collected by Prof. Hudson shows the cast of the interior 

 of a dorsal valve. There is a low^ median septum which extends 

 half-way to the front of the shell. At its posterior end it divides, 

 forming a low spond>lium as is usual in this genus. There is no car- 

 dinal process. 



Locality. — This species is common in the upper part of the I.ower 

 Chazy at McCollough's sugar-bush, at Chazy, New York, and is also 

 found at Valcour Island. The cotypes are in the Carnegie Museum. 



