19 



a width of 5 inches, thus indicating an animal of enormous size. 



Here the interesting query suggests itself, may this not be the 

 tail of the American Pterygotus? The largest size would well cor- 

 respond with the fragments of P. Cummingsi, Grote and Pitt (B. B. 

 S. N. S., Vol. III., 18), and the bilobed tail, figured by Professor 

 Huxley for'the English genus, does not differ sufficiently from our 

 specimens to contradict such an assumption. 



Several detached postoral plates of Pterygotus have been found, 

 the largest of which measures 2% inches in length and 1% 

 inches wide. 



3. Ceratiocaris grandis, n. sp. All fragments of this genus hither- 

 to described have been more or less crushed or broken. This 

 specimen, found in the same beds which yielded the Pterygotus, 

 consists of a complete carapace, which differs in its proportions 

 from any other species. The whole impression is very distinct, 

 and shows well the two valves. (Fig. 5.) The carapace is semi- 

 circular between the an- 



terior ends, nearly twice 

 as wide as long, measuring 

 9% inches in width by 

 5J4 inches in length ; / 

 the dorsal line is nearly \ 

 as semicircular as the an- 

 terior margin, and lightly 

 scalloped. The two valves 

 overlap each other about 

 a quarter of an inch, and 



x 3 

 Fis 



the division is visible for more than two-thirds of the length of the 

 carapace. Surface finely granulose. No ocular spots are visible. 



4. A specimen of JButhrolreftu Lesquereux, Grote and Pitt (B. B. 

 S. N. S., Vol. III., 88), found last summer, adds a little to the 

 knowledge of the structure of this Fucoid (Fig. 6); while the type ex- 

 hibits a number of branches irregularly mingled together, this spec- 

 imen shows the branches spread out. 



5. An examination of six more or less perfect specimens of Eury- 

 peterus pachycheirus proves that the figure of that species, as given by 



Professor Hall in the Paleontology of New York, Vol. III., Plate 82 



