268 NEW YORK STATE MUSEUM 
Horizon and localities. The four known specimens of this rare species, 
from Williamsville, Litchfield and Waterville, were obtained from the Bertie 
waterlime. 
Remarks. Hall clearly set forth the pecitliar characters of this 
species in the original description. He says ‘“‘ this species is distinguished 
by its robust, elongate body, the long straight-sided carapace, very anterior 
eyes, strong and thick jointed anterior feet, and extremely long swimming 
feet, with the great development of the terminal palette and the little 
dilation of the two preceding joints. The form of the postoral plate 1s 
very remarkable, though its posterior termination is unknown; the appen- 
dage is more prolonged and of a different form, and the adjacent articu- 
lation is very peculiar; and there are distinctive features in the maxillary 
plates.”’ | 
The exceedingly long spines of the first three pairs of legs, the bract- 
like appendages of the fourth pair, and the great anteroposterior. extension 
of the coxae of the last legs may be mentioned as further peculiar characters. 
The powerful, long spined first legs indicate that D. macro- 
chirus was an able walker and the bract-covered next pair of limbs, as 
well as the great elongation of the last pair, serve to demonstrate that it 
was likewise a powerful swimmer. 
In consequence of the active use it made of its swimming legs, the 
species appears to have developed strong internal keels [pl. 43] within some 
of the segments corresponding to the entapophyses or intetnal keels and 
bars in recent arthropods, serving as attachment bases for powerful 
muscles. 
Dolichopterus frankfortensis nov. 
Plate 83, figures 9-14 
The presence in the Frankfort shale fauna of at least one species with 
the characteristics of a Dolichopterus is demonstrated by a considerable 
number of carapaces and several metastomes. We refer these all for the 
present time to one species. 
Description. Carapace subquadrate; length and width about equal; 
‘frontal margin very bluntly angular in the middle; lateral margins nearly 
