1562 THE VOYAGE OF H.M.S. CHALLENGER. 



reach to the base of the peduncles of the third pair ; the outer ramus is a good deal 

 shorter than the inner, which in its turn is shorter than either ramus of the first 

 pair ; the third pair are similar to the second, and all three pairs agree in general 

 structure. 



Tiie Telson is oval in shape, with the base truncate, not coalesced with the preceding- 

 segment ; it reaches about halfway or rather further aloug the inner rami of the third 

 uropods. 



Length. — The specimen of which the lateral view is figured measured, in a straight line 

 from the front of the head to the back of the second pleon-segment, rather more than a 

 fifth of an inch. Fig. A was taken from a rather smaller specimen. 



Locality.— April 3, 1874, off Cape Howe, Australia; lat. 38° 7' S., long. 149° 18' E.; 

 surface, night; surface temperature, 66°"5. Fifteen specimens, of which ten were 

 probably (and some of them certainly) females, the other five being adult or young- 

 males. 



Remarks. — The specific name is derived from rrXaTvs, wide, and pvyxos, beak, in 

 allusion to the breadth of the head. 



This species is very like Daira (f ) dehilis, Dana, but in that species the joints of the 

 antennae are described and figured as all short, there is no rostral point on the under side 

 of the head, the branchial vesicle of the second perseopod is figured as shorter than the 

 first joint, the fifth and sixth coalesced pleon-segments are drawn as longer than the fourth, 

 and the telson is represented as coalesced with the preceding segment ; the back of the 

 animal is drawn as if strongly imbricated. Dana's specimen, three lines long, was taken 

 in lat. 2° S., long. 175° W. When Dana says that in the second gnathopods the 

 carpus is hardly smaller than the hand, he is no doubt speaking of the third and fourth 

 joints respectively, not of the fourth and fifth, but either way his remark is inappli- 

 cable to our species ; he figures the wrist of the second gnathopods with the inner or 

 front margin smooth. Thamneus rostratus, Bovallius, must also come near to the 

 present species, but that has the "telson very broad, rounded, a little shorter than 

 last pair of uropoda." It ought to be mentioned that among the Challenger speci- 

 mens three of the female specimens were much bulkier than the rest, and lighter 

 coloured, so that till the details were compared these three were considered specifically 

 distinct from the others. 



