THE EURYPTERIDA OF NEW YORK 231 
The presence of the genus Eusarcus in the Frankfort fauna is demon- 
strated by various characteristic parts of the integument, viz, two forms 
of carapaces, cordiform metastomas so typical of Eusarcus, extremely 
broad and short tergites, the long conical postabdominal segments, a telson, 
and fragments with the characteristic ornamentation. The metastomas are 
probably the most conclusive of these, no other genus having furnished 
singularly broad and short subtriangular plates. 
The two species here described are for the present entirely based on 
the carapaces and the other parts of the integument are noted below.' 
The genus hence comprises the following species: 
Eusarcus scorpionis Grote & Pitt E. raniceps (H. Woodward) 
[encl. E. giganteus Grote & Putt] 
E. newlini (Claypole) . acrocephalus (Semper) 
E. scoticus (Laurie) 
E 
[encl. E. ingens (Claypole)] E. simonsoni (Schmidt) 
E. punctatus (Salter) E 
E. scorpioides (H. Woodward) E 
?E. obesus (H. Woodward) 
. longiceps nov. 
. triangulatus nov. 
margins making horseshoe-shaped impressions, is characteristic of Eusarcus as fully 
stated in the generic description. The clear photographs of the type of the Russian 
species show that the general outline and the form of the attached last leg possess the 
characteristics of Eusarcus. The detached part is not a leg as surmised by Schmidt 
but the scorpioid slender postabdomen of Eusarcus, and furnishes another character 
typical of that genus. As to the ‘‘ Dorsalfurchen ’’ we have the impression that they 
are accidental. Less pronounced furrows have been noticed by us in various speci- 
mens of Eurypterus remipes and other species. 
The abdomen appears relatively a little longer than in our species of Eusarcus, 
possibly through a pulling apart of the segments in anteroposterior direction. 
| Other appendages referable to Eusarcus in the Frankfort shale. We reproduce three 
metastomas which, by their cordiform outline indicate that they probably belong to a 
type that is either identical or closely related with Eusarcus. The smallest of the three 
[pl. 84, fig. 10] is covered with flat, round tubercles that agree with those of the integu- 
ment of E. scorpionis. Another possesses small, granular tybercles [pl. 84, fig. 11]. 
Our collection also contains the characteristic long conical tail segments and in one 
case a segment with attached curved telson spine; this and a few tergites suggest the 
preabdomen of a Eusarcus. 
