8 T. V. IlOIXiSON. 



In tlio female the Krst appeudage of the mesosome is comparatively small ; the 

 ischium is produced as a rounded lobe, much narrower than that of the male, below 

 the p)iiit of its articulation ; the merus is not very different to that of the male ; 

 the carpus is cylindrical ; both these joints bear a pair of long setae. The propodus 

 forms a well-developetl chela ; the two dactyli are stout and sulicqual in size, with 

 discoloured teeth at their extremities. The immovable finger has a long seta on 

 either side of its base and another pair on the inner margin clo.se to a .series of four 

 small teeth which end against the terminal tooth. 



In the female the first leg is slender, the first joint is us long as the succeeding 

 four, the .second is very short, and the others progre-ssively lengthen and have a few 

 setse distally ; the seta) are strongest at the extremity of the limb ; the terminal 

 claw is very slender and more than half the length of the joint which bears it. 

 The two following legs are similar, but the terminal claw shortens. The last three 

 pair are a little shorter and stouter, the .setaj are more spinous, and the terminal 

 claw is comparatively short and more definitely a claw. Tho.se of the male are 

 similar, but longer and more slender. The oostegites number four pairs, and are 

 attached from the second to the fifth appendages of the mesosome. Each oostegite 

 .consists of a rather broad strap-like axis, from each side of which extends a very 

 delicate membrane, the whole forming a concave structure nearly round in shape. 



The pleopods are five pairs of the appendages adapted for respiration, and are 

 similar in both sexes. Each consists of a protopodite of two joints, the first of which 

 is very small, a large endopodite, ovoid in shape, the inner margin of which is fringed 

 with stiff setse, and these increase in size to the distal extremity. The exopodite 

 is much smaller, slightly curved, and its inner margin is similarly .setose, but the 

 setae are much reduced in number ; the posterior pleopoda ditl'er slightly in shape. 

 The exopodite is attached half way along the second joint of the protopodite. 



A very large number of specimens were collected during the whole of our stay 

 in Winter Quarters. They were constantly being picked out of the sponge debris and 

 obtained inside the 25-fathom line. It would appear from the great number of 

 individuals of all ages and sizes that the acquisition by the male of the enormously 

 developed chelipeds takes place suddenly. There were no specimens which indicate 

 a gradual development of these organs, nor were there any specimens of small size 

 showing this distinctly masculine character. A large proportion of the apparently 

 adult females show no trace of oostegites, and it is quite po.ssible that some at least 

 were not completely developed males. The .suddenness of the change is also 

 emphasize<l by the fact that the mouth organs of the fully developed male are 

 defective. 



LEl'T.\NTHri!.\. 



Leplanthuni (i. O. Sjirs (13), \>\). 47- IS. 



This genus was instituted by Prof G. (). Sars in 1899, being separated from 

 Paranthuni liy a number of small characters. The mouth organs seem to be the 



