REPORT ON THE ISOPODA. . 105 



The anterior dorsal margin of the head is excavated by a deep semicircular notch ; 

 the lateral margins of the head are straight. The eyes are large and, as is so usually 

 the case in this genus, are triangular in form. The whole surface of the head is closely 

 covered with tubercles, of which two on either side of the median line and rather behind 

 the eyes are larger and more conspicuous than the rest. 



The body is broadest at the third thoracic segment ; the fourth segment is, however, 

 the longest. Each of the first four thoracic segments is ridged posteriorly ; laterally 

 the ridge widens out and comes to occupy the whole of the segment. The lateral 

 margins of the terga project outwards beyond the epimera into a blunt smooth 

 process. 



On either side of the dorsal median line the posterior ridge bears two longish blunt 

 spines, which are shorter in the first and fourth segments than in the two middle ones, 

 where they are subequal. 



The anterior region of each of these segments is also ridged and tubercular. 



The three posterior segments of the thorax are likewise beset with numerous 

 tubercles, a pair of which, one on either side of the dorsal median line, are stouter than 

 the rest but not nearly so marked as are the corresponding spines of the anterior thoracic 

 segments. 



The caudal shield is ovoid, and terminates in two moderately long spines which are 

 directed rather outwards ; the surface of the caudal shield is beset with numerous 

 tubercles which appear to be rather longer than those which cover the rest of the body ; 

 they are pointed and directed backwards. 



The antennse have unfortunately lost the flagella ; the length of the peduncle is 

 19 mm.; the last two joints are elongated and increase progressively in length. The 

 basal joints are roughened and tubercular, and the same is the case with the thoracic 

 limbs (figs. 7, 8) and uropoda. 



Station 313, January 20, 1876 ; lat. 52° 20' S., long. 67° 39' W.; depth, 55 fathoms ; 

 bottom temperature, 47°'8 F. ; sand. 



Arcturus stebbingi, n. sp. (PL XXIV. figs. 1-4). 



This species is only represented by a single individual, a mature female with brood 

 cavity developed ; it was dredged in shallow water, 30 fathoms, off Kerguelen. I take 

 the opportunity of dedicating the present species to the Rev. T. E. R. Stebbing, who has 

 paid special attention to this genus. 



Arcturus stebbingi cannot be confounded with either Arcturus furcatus or Arcturus 

 studeri ; for in both of these species the body is decked with long and numerous spines ; in 

 the present species the body is extremely tubercular, but only a pair of tubercles, on the 



(ZOOL. GHALL. EXP. —PART XLVIII. — 1886.) Ebb 14 



