62 NEW YORK STATE MUSEUM 



In mature specimens this feature is not observable. It is, how- 

 ever, known in European forms and has been recognized by Pom- 

 pecki in specimens of Illaenus comas (pi. 3, fig. 19) 

 and 1 . 1 i n n a r s s o n i ? . The two lunate cicatrices in front 

 of the siigmoidal curves mentioned by Dr Clarke 1 from casts from 

 the Galena limestone at Wykoff, are distinctly noticeable on some 

 of these casts. ■ Illaenus a m e r i e a n u s is restricted in 

 Canada, New York, and western localities, to the Trenton and can 

 therefore be considered a good index fossil of that formation. 

 Dr White has however lately reported this species as occurring 

 also in the Black river beds of the Rathbone creek section on the 

 West Canada creek near Trenton Falls. (Groups 5, 7) 



thaleops Conrad 

 Thaleops ovata Conrad. Acad. nat. sci. Phil. Proc. 1843. 1:332 



Two pygidia from the gray crystalline limestone agree with 

 the descriptions of this part of the carapace of Thaleops 

 ovata given by Conrad and later authors. Thaleops 

 ovata has thus far been found in the Mississippi and Ohio 

 basins, as well as in Canada, only in beds corresponding to the 

 New York Lowville limestone. (Group 7) 



cyphaspis Burmeister 

 Cyphaspis matutina sp. nov. 

 PL 4, fig. 5, 6, 7 



Two small cranidia belonging to the genus Cyphaspis were 

 found in the black limestone. The glabella is short, roundish 

 suibquadrangular, moderately and uniformly convex, sloping 

 equally to all sides; surrounded by deep dorsal 1 furrows and an 

 equally deep frontal furrow. Three pairs of glabellar fur- 

 rows are discernible, the first two faint, short and oblique, the 

 third semicircular, extending to the occipital furrow, and sepa- 

 rating a pair of less convex lobes, which extend a little beyond 

 the lateral margin of the first and second lobes ; the broad border 

 slopes steeply to a narrow rim, somewhat upturned at the mar- 

 gin. The two specimens differ considerably in size, the one 



i Geol. Minn. Pal. 1897. v. 3, pt. 2, p. 715. 



