REPORT ON THE ISOPODA. 63 



The amhulatory limbs are rather slender, and the joints elongated ; the fourth is always 

 longer than either the preceding or succeeding joint ; the spines upon these appendages 

 are not very much developed ; the second and third joints in all bear a few pinnate hairs 

 upon the inner margin close to the articulation with the succeeding joint ; the remainder 

 of the limb is furnished with delicate sword-like spines arranged in tufts ujjon the inner 

 side ; mixed with these are a few strong serrated spines which are most abundant upon the 

 distal extremity of the penultimate joint. The inner side of the third, fourth, and fiftli 

 joints in the last ambulatory limb (PI. III. fig. 11) is covered with soft pinnate hairs (fig. 12), 

 like those found ou the second pair of thoracic appendages of the male, and the inner side 

 of the first ambulatory limb is similarly provided with these hairs, though to a less extent. 



The three anterior abdominal appendages are like those of other species ; the liasal 

 joint is prolonged outwards, and bears two to three branched hairs at the tip. 



The suture which divides the exopodite of the opercula is oblique ; the exopodite of 

 the gill appendage is bifurcate. 



Station 120, September 9, 1873; lat. 8° 37' S., long. 34° 28' W.; 675 fathoms; 

 bottom, red mud. 



10. Serolis antarctica, F. E. B. (PI. III. figs. 1-6). 



Serolis anfardica, F. E. Beddard, Proc. Zool. Soc. Lond., 1884, pt. iii. p. 333. 



The three species above described agree with each other and diS'er from all other known 

 species of the genus in the great development of the epimera. Serolis antarctica, the 

 only other deep-sea form, has com^jaratively short, flat epimera as in the shallow-water 

 species of Serolis. This species may be distinguished by the entire absence of eyes, and 

 by the strongly marked sculpturing upon the dorsal surface of the body. 



The Challenger collection contains eight specimens besides some fragments. The 

 four male specimens are all approximately of the same length, the largest measuring 

 33 mm. in length by 31 mm. in greatest breadth. The remaining specimens, which are 

 females, vary in size; the largest measures 31 mm. in length by 26 mm. in greatest breadth. 

 The males, therefore, ap^aear to be larger than the females, and also broader in proportion 

 to their length ; the contour of the body in the males is oval, in the females somewhat 

 pear-shaped {cf. PI. III. figs. 1, 3); the epimera are proportionately longer in the 

 males, those of the sixth pair jjroject a little way beyond the end of the caudal shield; 

 the abdominal epimera are much the same length in the two sexes, and reach about half- 

 way down the caudal shield ; in the female the sixth thoracic epimera do not project 

 beyond the caudal shield ; the second pair of abdominal e})imera are a trifle longer than 

 the anterior pair, and both are very slightly shorter than the abdominal epimera in the 

 male. The sterna of the abdominal segments do not seem to diff"er in the two sexes. 

 The colour of this species (in alcohol) is violet-blue, iucliuiug to reddish yellow in the 

 middle of the body. The body has a nacreous glitter when seen by oblique light. 



