REPORT ON THE ISOPODA. 57 



shield are somewhat differeut from those figured and described in the type specimens ; a 

 strong ridge runs parallel to the outer margin of the epimera ; at its upper extremity it 

 bends backwards and passes for a short distance parallel to the boundary line of the 

 cephalic shield, terminating a little below the ridge which crosses the latter ; the transverse 

 ridge, which indicates the division of the epimeron into two parts corresponding to the 

 first two thoracic segments, is very slight ; the anterior spine-like process of these epimera 

 is not present, and the anterior margin is in consequence quite smooth (fig. 3). Many of 

 these specimens are more darkly coloured. 



In a small specimen from Station IGtc (400 fathoms), measuring 16 mm. in length, 

 the outer ridge upon the anterior epimera is not present, but the abdominal epimera have 

 the same characters as those of the type specimens. 



Station 156, February 26, 1874; lat. 62° 26' S., long. 95° 44' E. ; 1975 fathoms; 

 bottom. Diatom ooze. 



Station 164c, June 13, 1874 ; lat. 34° 19' S., long. 151° 31' E. ; 400 fathoms ; bottom, 

 green mud. 



Station 168, July 8, 1874 ; lat. 40° 28' S., long. 177° 43' E. ; 1100 fathoms ; bottom, 

 Ijlue mud. 



Station 169, July 10, 1874 ; lat. 37° 34' S., long. 179° 22' E. ; 700 fathoms ; bottom, 

 blue mud. 



8. Serolis necera, F. E. B. (PI. V. figs. 1- 11). 



Serolis necera, F. E. BeJJanl, Proc. Zool. Soc. Lond., 1884, pt. iii. p. 331. 



This species almost rivals Sei'oUs bromleyana in size, and resembles it in the great 

 length of its spiniform epimera. 



The largest male measures 42 mm. in length and 48 mm. in breadth ; the largest 

 female measures 41 mm. in leno'th and about 40 mm. in breadth. The difference in 

 the proportion of length to breadth in the two sexes is caused by the greater develop- 

 ment of the epimera in the male ; the two sexes also differ in the characters of the sterna 

 of the abdominal segments and in the frontal " sense organ," which is much larger and 

 more evident in the female {cf. figs. 1 and 3) ; there is not such a marked difference be- 

 tween the lengths of the abdominal epimera in the two sexes as is often found in the 

 other species of Serolis. 



Cephalic Shield. — The eyes are unusually large and conspicuous, 6 mm. long, bluish 

 black in colour owing to the comparatively small amount of pigment present; the 

 diameter of the cephalic shield is greater than its length ; as in Serolis hromleyana, a 

 transverse ridge passes from the base of the rostrum to the lateral margins of the cephalic 

 shield, and cuts off a small antero-lateral portion ; the anterior margin of this as well as 

 of the first epimera is bent upwards. Between the eyes are a number of spiniform pro- 



(ZOOL. CHALL. EXP. — PART XSXUI. — 1884.) K^k 8 



