356 MEMOIRS OF THE CARNEGIE MUSEUM 



There is a brown {cJicstiiuf, \V, 9) spot on the anterior margin of the carapace on 

 each side below the eyes, not noticed by Faxon. The brown bands of the abdomen 

 are hwnit sieniiu [IV, 6). In the middle of the abdomen the epimera are hazel (IV, 

 12). The color of the hnger tips is ferrugineous (IV, 10), often paler, the preceding 

 band is dark olive-green, often almost black. The articular tubercles on the lower 

 side of the hand are taimg (V, 1), on the upper side they are darlc-green. The 

 articular membranes of the chelfe are ■w'mepui'jdc (VIII, 15). The darker green of 

 the carapace is generally confined to distinct large blotches, symmetrically disposed ; 

 one pair on the gastric region, and one each t)n the anterior and the posterior part 

 of the brancliial regions. ( Jften the two blotches of the gastric region run together, 

 which may also be the case with those of the branchial regions. They often appear 

 spotted or mottled with the lighter, or rather more l)rownish (tawn}' olive), ground 

 color. The brown spot on the anterior margin of the carapace is sometimes indis- 

 tinct, and in young specimens with fresh shells, it may have a trace of yellow 

 below. All these colors are bright and distinct only in fresh shells. On old shells, 

 a coat of mud is generally deposited, giving to the whole body a dirty blackish 

 color, and besides, the colors themselves fade considerably, so that only a dirty olive- 

 green remains, with some brown on the abdomen. 



The color of neAvly laid eggs under the abdomen of the female is olive-green (X, 

 18). 



The above description is founded upi)n the examination of one hundred and 

 twenty-one specimens, now preserved in the collections of the Carnegie Museum. 

 Fifty-six of these specimens are from the state of Pennsylvania, fifty-four from 

 New Jersey, eight from Maryland, and three from West Virginia (Potomac River 

 at Cherry Run, Morgan County). This, however, does not represent the total num- 

 ber of specimens seen by the writer, since many others were collected by him, as 

 well as seen in the collections of the Department of Agriculture of Pennsylvania, of 

 the Academy of Natural Sciences in Philadelphia, and of Olierlin College. 



DISTRIBUTION.' 



LOCALITIES REPRESENTED IN THE COLLECTIONS OF THE CARNEGIE 



MI'SEUM. 



Pennsylvania : Bucks Co., Delaware River, New Hope ; Delaware River, Penns 

 Manor; Little Neshaminy Creek, Grenoble ; ComnKjn Creek, TuUytown ; J'hihi- 

 delphia (Jo., Delaware River, Torresdale Fish Hatchery, Torresdale ; Delaware 



' All localities without ttirtlier record have been ascertained by the writer in person. In other cases the authority 

 (when published), or the collector and institution, where the specimens are preserved, is given. 



