24 
PALAEONTOLOGY OF NEW-YORK. 
40. 2. ILLiENUS CRASSICAUDA? 
Pl. IV. (bis). Fig. 13. 
Entomostracites erassicauda. Wahlenbeeg in Nov. Act. Reg. Soc. Upsal. 1821. Vol. viii. pag. 27. tab. ii.; 
pag. 294. tab. vii. fig. 5, 0. 
Illamus erassicauda. Dalman, K. Vet. Acad Handl. 1826. Pag. 65. tab. v. fig. 2 a - e. 
— — Hisinger, Pet. Suecica, 1837. Tab. iii. fig. 5. 
Fragment of buckler. Large, sub-hemispherical, gibbous, very thick and strong; front 
margin involute. 
The portion remaining is essentially the central lobe of the buckler, the lateral portions 
having separated at the sutures. The specimen is more gibbous than common ; but on 
comparison with the figures above quoted, and with a perfect specimen from Russia, there 
appears to be no reason to doubt the specific identity. 
Position and locality. In subcrystalline oolitic limestone at Chazy in Clinton county, and 
in Galway, Saratoga county. 
41. 1. ASAPHUS'? OBTUSUS (n. sp.). 
Pl. IV. (bis). Fig. 14. 
Caudal extremity semicircular, twice as wide as long ; surface finely granulated or 
smooth ; marginal expansion even, and not depressed as in Isotelus ; central lobe faintly 
visible by a gentle depression on each side ; no marks of articulations. 
This fossil varies from Isotelus , in the extremity being destitute of the apparent articula¬ 
tions which are seen in species of that genus ; and also in the marginal expansion being 
plain, and not depressed near the margin, as well as in being punctulated, and exhibiting 
none of those fine linings seen in the margin of Isotelus, Ill^nus and Bumastis. 
This fossil bears some resemblance to the caudal extremity of Asaphus palpebrosus, but 
the central lobe is less distinct than in that species. The middle lobe is less distinct, and 
the whole shell more evenly convex and smooth than any specimens of the Isotelus of 
the Trenton limestone. 
Position and locality. This species occurs in the compact limestone near the base of the 
formation, and where the rock is but little changed from the character of the Calciferous 
sandstone. It has been found only at Chazy village, Clinton county. (State Collection.) 
42. 2. ASAPHUS MARGINALIS ( n. sp.). 
Pl. IV. (bis). Fig. 15. 
Caudal extremity semi-elliptical, distinctly three-lobed, marked by 7 or 8 distinct 
pseudo-articulations, which are duplicate on the lateral lobes; articulations not reaching 
the margin, but terminating in a crustaceous marginal expansion, which is depressed of 
channelled near the edge as in Isotelus ; surface granulated. 
