1416 THE VOYAGE OF H.M.S. CHALLENGER. 



those of the third, distally a little broader, with the inner apex acutely produced ; the 

 inner ramus broadly lanceolate, almost as long as the peduncle, longer than any of the 

 other rami ; the outer ramus much narrower and shorter, longer than the outer ramus of 

 either of the other pairs ; peduncles of the third pair longer than those of the second ; 

 the rami respectively a little smaller than those of the second pair. 



Telson triangular, a little longer than the breadth at the base, not a quarter the length 

 of the peduncles of the third uropods, the apex slightly rounded. 



Length of the specimen figured, more than nine-tenths of an inch. 



Localities. — Station 146, December 29, 1873 ; between Marion Island and the Crozet 

 Islands; lat. 46° 46' S., long. 45° 31' E.; surface, daytime; surface temperature, 43°. 

 Two specimens about nine-tenths of an inch long, three about six -tenths of an inch, seven 

 or eight a quarter of an inch or less. 



Station 147a, January 1, 1874; off Crozet Islands; lat. 46° 45' S., long. 50° 42' E.; 

 surface ; surface temperature, 42°. One specimen. 



Station 158, March 7, 1874; in the Southern Ocean; lat. 50° 1' S., long. 123° 4' 

 E.; surface ; surface temperature, 45°. Three specimens. 



March 9 and 10, 1874 ; south of Australia ; lat. 48° 18' S., long. 130° 4' E.; surface ; 

 surface temperature, 50°. Six specimens. 



Remarks. — The species appears to stand extremely near to the northern Euthemisto 

 bisjnnosa (Boeck). The peculiarities of the fourth joint in the first and second perseo- 

 pods and of the fifth joint of the third perseopods in the specimen figured from Station 

 146 are, I think, only individual peculiarities. They led me to suppose that the species 

 belonged to the genus Parathemisto (see Note on G. M. Thomson, 1879, p. 500). In 

 Dana's Themisto antarctica, to which Mr. Thomson assigns the species, the back is not 

 dentate, and the third perseopods are, as in other species of this genus, very strikingly 

 longer than the fourth and fifth. The present species therefore seems to me to be 

 distinct, and as the name antarctica is preoccupied, I have renamed it in compliment to 

 Mr. G. M. Thomson. 



Numerous small specimens, labelled " February 2, 1874, Antarctic Ocean, surface," and 

 " February 3, 1874, between Kerguelen and Heard Island, surface," appear to belong to this 

 species, the third perseopods not being elongate, but the specimens are young, 1 with the 

 backs rounded not dentate, the wrist process of the second gnathopods not very elongate. 



One specimen, from Station 149b, January 17, 1874, lat. 49° 28' S., long. 70° 30' K, 

 25 fathoms, measuring seven-tenths of an inch, is distinguished from the rest by having 

 the third peraeopods very long, the dorsal teeth proportionately to the length of the animal 

 very small, and the head and body scabrous with a fine down. Should it be necessary to 

 separate this specimen from the other, I would propose for it the name Euthemisto scabra. 



1 Compare Hansen's remarks on the young of Themisto bispinosa, quoted p. 1409. 



