OUTMANN : THE CUAWKISHIiS OF THE STATE OF PENNSYLVANIA 379 



it proxiinally. Ijower surface with a Ijlunt conical tul)ercle in the middle of the 

 anterior margin (occasionally spiniform). The tubercle at the articulation with the 

 hand is generally obsolete. There are sometimes additional tubercles ; the one 

 which most frequently occurs is a small spine or tubercle between the large one on 

 the inner margin and that on the anterior margin of the lower side. 



Meropodite smooth, with 1-3 tubercles near the distal end of the upper margin, 

 one of which is often spiniform in young specimens; in old specimens they are 

 generally very indistinct or wanting. Lower .side witli two rows of spiniform 

 tubercles. Tlu' outer rows consist of 1-6 (very rarely <jnly (jne tubercle). Six were 

 found in only one instance, that of a regenerated cheliped. (Generally there are 

 two or three. The inner row has (j-11 spiniform tubercles, of which the distal is 

 the largest. A small tul)ercle on the outer articulation with the carpopodite may 

 be present or aljsent. 



Ischiopodite of third pereiopod hooked in the male. The hook of the first form 

 is strong and subconical. 



The coxopodite of the fourth pereiopod in the male possesses a prominent rounded 

 and compressed tubercle. 



Fird pleo'pods of the male of the first form (Plate XXX IX. Fig. 8) stout and 

 short, reaching to the posterior margin of tlie coxopodite of the third pereiopods. 

 They are not articulated at the base. The two parts are separated at the tips for a 

 short distance, and both are curved sharpl}' backward, forming almost a right angle 

 with the basal part. Distally they are partly twisted, so that the outer part is 

 directly anterior to the innei-. The outer part is horny, compressed, falciform, the 

 tip pointed, with a small posterior accessor}' point (often worn off). The inner 

 part is soft, swollen at the base, and suddenly tapering to a blunt point. 



In the male of the second form this organ may be articulated at the base (in the 

 case of the young) or not articulated (in older specimens). Both jnirts are separated 

 distally for a short distance, and the outer part is soft, not horny, le.-^ distinctly 

 compressed, and Muiit. In the young these organs are considerably shorter than in 

 older specimens. 



Aimulus ventndis of the female transver.sely rhombiform, with a deep central 

 depression and a longitudinal S-shaped fissure. Anterior and more particularly the 

 posterior margins elevated. The whole anterior portion of the annulus often apj)eai-s 

 depressed compared with the elevated posterior margin, ^^'here the longitudinal 

 fissure passes over the posterior margin the latter is slightly depressed. In young 

 females the central depression is less marked, and tlie margins are consequently less 

 elevated, giving a rather fiat appearance on the annulus. 



