linliaii hc<'ji-sca Drciijlnij. 271 



those ot' the Cran^'oiiiiho, uMiicIi tlioy clu.scly rcscnihlc, and 

 from whicli they ehicHy did'er in their .sci.ssor.s-like extremity. 

 Tliey present but six clistinet true joints, one of the bhi(h;s of 

 the terminal scissors having to be interpreted as a movably 

 artieuhited prolongation of the proj)odite, and the tiiird and 

 fourtli joints being all but indistinguishably fused together. 

 The iirst two joints are short. The third j'>int, which is 

 strongly curved like the corresponding joint of the external 

 maxillipede, increases slightly in thickness from the base to 

 the apex, where its upper margin is prolonged into a sharp 

 needle-like s{)ine preceded by a few spinules. Tiie fourth 

 joint, short and obconic, also bears a similar spine in corre- 

 sponding position. The fifth joint, or propodite, is oblong 

 and somewdiat compressed, it bears at the distal end two 

 equal and movably articulated toothed knife-like blades- 

 one answering to .the iixed ])rolongation of the propodite, the 

 other to the dactylopodite of the typical crustacean chela, — 

 Avhich are evidently capable of playing upon one another like 

 the blades of a pair ot scissors or shears. 



The legs of the second ])air are also oidy six jointed, the 

 third and fourth joints being all but indistinguishably fused 

 together. They ditfer remarkably in form from the preceding. 

 The first two joints are as in the legs of the first pair. The 

 third joint is a cylindrical rod armed with a few minute 

 spinules on the upper margin, which terminates in a sharp 

 spine. The fourth joint is also cylindrical, but shorter and 

 much thinner than the preceding, and unarmed. Tiie fifth 

 joint, likewise cylindrical, is about half as long as the pre- 

 ceding and tapers slightly to its apex, where it bears a com- 

 pactly coned pencil of possibly expansile set^. The sixth 

 joint is a minute, transversely elongated, nodular rudiment, 

 lodged in a notch of the upper and outer margin of the distal 

 end of the propodite. 



The three remaining pairs of legs are quite different from 

 tlieir predecessors, and are substantially alike, differing from 

 one another only in length and in the degree to wliich the 

 fusion of their third and fourth joints has been carried. They 

 are typical ambulatory limbs. The second only slightly 

 exceeds the first, while the last, owing mainly to the great 

 elongation of its propodite, greatly exceeds the second in 

 length. Thev are roughly cylindrical and are armed below 

 and on the contiguous parts of their sides throughout with 

 sharp spinules, which in tlie fourth joint or meropodite assume 

 an arrangement in two rows on the ventral edges of the 

 joint, while the apices of the meropodite and of the obconic 

 carpopodite each bear one median dorsal and at least one 



