532 THE VOYAGE OF H.M.S. CHALLENGER. 



The form of the first pair of pereiopoda exactly corresponds with the dermal tissue, 

 excepting that the chelate hand appears to be formed within a case in which the fingers 

 are enclosed within one sac. The second pair is still more evidently undergoing a change, 

 for not only is the hand with its two fingers confined in one and the same sac, but the 

 five articuli of the carpos are enclosed within one continuous envelope, which is minutely 

 corrugated, as if it had the capacity of being stretched by the growth of the included 

 organ. 



The third and fourth pairs of pereiopoda are also visible within the outer sac, through 

 the extremity of which the point of the dactylos appears to force its way. 



The outer plates of the rhipidura and telson are also seen to be undergoing a change 

 within the exuvium; the outer branch appears to be dividing to form the diaeresis, and the 

 hairs at the extremity are all telescoped in their length, as if on being liberated they were 

 caj)able of shooting out to their full extent. 



Parathanas imrnaturus, n. sp. 



A damaged specimen of what appears to be another species was taken in the same 

 region, in Zebu Harbour, in January 1875, at the surface of the sea. 



The only distinguishable difference is that the rostrum is longer in proportion to the 

 animal, which has a length of scarcely 5 mm. (0'19 in.). 



Unfortunately all the pereiopoda are broken off short, and there is little to determine 

 the true character of the specimen. 



Cheirothrix, n. gen. 



Carapace anteriorly produced to a sharp rostrum that is separated by a groove from 

 the orbital lobes, which are anteriorly produced to a sharp point. Fronto-lateral angle 

 produced to a point. Anterior somites of the pleon as deep as the carapace. 



Ophthalmopoda reduced to a minimum and concealed beneath the frontal margin of 

 the carapace. 



First pair of antenna? biramose and furnished with a well-developed stylocerite. 



Second pair furnished with a short and broad foliaceous scaphocerite, which is 

 strengthened on the outer side by a rigid margin and a small tooth. 



First pair of gnathopoda having the terminal joints reflexed, the basis carrying a long 

 and slender ecphysis. 



The second pair is slender, four-jointed, and pediform. 



The first pair of pereiopoda has large chelse. The second pair is shorter than the 

 third, slender, having a carpos with five articuli, and terminating in an extremely minute 



