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



The specific characters of Arcturus furcatus are as follows : — 



The length of the largest specimen, a male, is 41 mm., the antenna- measure 44 mm. 



It most closely resembles Arcturus sjnnosus, but differs from that species in a 

 number of characters, and is clearly distinct. 



The antero-lateral margin of the head (PL XXV. fig. 6) is furnished with a short 

 forwardly directed spine which is wanting in Arcturus spinosus. 



Between the eyes are a pair of loDg spines, which instead of being nearly parallel to 

 each other in their direction as in the latter species, are inclined outwards nearly at 

 right angles ; behind these are a pair of shorter spines, and the hinder region of the 

 head is covered with tubercles. 



Of the four anterior thoracic segments the fourth is the longest ; each of the 

 segments bears a stout ridge posteriorly, covered with spines and tubercles, which are 

 disposed as in the females of Arcturus spinosus (see description, p. 88), the spines are 

 shorter and blunter than in the males of that species and are more abundant ; the 

 tubercles between the spines are also better developed. 



The most striking difference between the two species is in the abdominal segments 

 and the caudal shield ; in Arcturus spinosus, as already mentioned, the two sexes differ 

 in the relative development of tubercles in this region of the body ; they are much 

 more strongly marked in the female than in the male. In both sexes of Arcturus 

 furcatus the abdominal segments and the caudal shield are covered with numerous stout 

 short spines of unequal length, and curved backwards ; a comparison of my figures of 

 Arcturus spinosus (PI. XX. figs. 1, 2) with Studer's figure of Arctu rus furcatus (loc. cit., 

 pi. i. fig. 3) will show this difference, which is very striking and serves at once to 

 distinguish the two species. 



Betsy Cove. Kerguelen, January 14, 1874 ; depth, 7 fathoms; volcanic mud. 



Station 149b, off Royal Sound, Kerguelen, January 17, 1874; lat. 49° 28' S., long. 

 70° 30' E. ; depth, 25 fathoms ; volcanic mud. 



Station 149h, off Cumberland Bay, Kerguelen, January 29, 1874; lat. 48° 45' S., 

 long. 69° 14' E. ; depth, 127 fathoms; volcanic mud. 



Station 151, off Heard Island, February 7, 1874; lat. 52° 59' 30" S., long. 

 73° 33' 30" E. ; depth, 75 fathoms ; volcanic mud. 



Station 153, Southern Ocean, February 14, 1874; lat. 65° 42' S., long. 79° 49' E.; 

 depth, 1675 fathoms; bottom, blue mud. 



Arcturus (facialis, F. E. Beddard (PI. XXI. figs. 1-4). 



Arcturus glOcialie, F. E. Beddard, Proc. Zool. Soe. Lond., 1886, pt. i. p. 111. 



This new species of Arcturus agrees with Arcturus spinosus and Arcturus furcatus 

 in the extraordinary development of spines upon the carapace and limbs ; it comes 



