REPORT ON THE CRUSTACEA MACRURA. 



785 



The second pair of gnathopoda has the antepenultimate joint, which I take to be the 

 ischium and meros united, deeply arched downwards ; the basis is furnished with an 

 ecphysis that reaches to the distal extremity of the meros, and connected with the 

 appendage is a small branchial plume that appears to be attached to the coxal articula- 

 tion, and is, therefore, arthrobranchial in character. 



The first pair of pereiopoda is slender, chelate, and extends to a point subequal with the 

 apex of the rostrum ; the fingers are longer than the palm, and the carpos is as long as 

 the propodos, including the palm and dactyloid process. The second pair is longer and 

 more robust than the first ; it is chelate and has the fingers longer than the palm, which 

 is subcylindrical, and subequal in length with the carpos. The three succeeding pairs 

 are uniform in size and character ; the meros is longer than the ischium, the carpos is a 

 little more than half the length of the meros and projects at the anterior distal angle 

 over the propodal articulation ; the propodos is twice the length of the carpos, and is 

 furnished with several solitary spines on the anterior and posterior margins ; the 

 dactylos is curved, smooth, and uniunguiculate. 



The branchiae correspond in arrangement with those of Pcdiemon serratus. 



Female. — Differs from the male in being shorter and more robust generally, and in 

 having the rostrum shorter in proportion to the length of the carapace, and deeper 

 anteriorly, assuming more the shape : ' d'unfer de lance* mentioned by Milne-Edwards. 



Length, entire, 



„ of carapace, 



„ of rostrum, 



„ of pleon, . 



„ of third somite of pleon, 



„ of sixth somite of pleon, 



,, of telson, . 



Habitat. — Gulf-weed, Atlantic, April 1873. 

 females rather preponderating. 



One hundred and thirteen specimens, 



The original specimen from which Milne-Edwards drew up his description was found in 

 the Indian Ocean, upon some floating weed. Desmarest obtained his specimen [Leander 

 erraticus) from the Atlantic, at about 100 to 150 leagues off the coast of Guadeloupe. 

 Dr. Stimpson's specimen, which he takes to be the same as Leander of Desmarest, was 

 found to be common amongst the Sargasso-weed in the Atlantic, between 30° and 35° 

 north of the equator. 



It was from this region that the specimens in the Challenger collection were also 

 taken, and they correspond both generally and in detail with the description given by 

 Milne-Edwards, excepting that they have nine teeth on the upper surface of the rostrum 

 in the male, and four on the lower margin, and twelve on the upper margin in the 



(ZOOL. CHALL. ESP. PAKT LII. — 1887.) Fff 99 



