1*26 THE VOYAGE OF H.M.S. CHALLENGER. 



elongate-ovate, equal in length to the last three abdominal segments, inner margin 

 ending in a small spine-like seta ; two setae on external margin, and two at apex. Eyes 

 contiguous. In the male the posterior angle of each abdominal segment is produced 

 into a minute tooth ; the segments are not marginally serrated, but the last three bear 

 median crests, which are minutely serrated at the extremities. 



Habitat. — Off' St. Vincent, Cape Verde, April 26, 1876; in hit. 13° 50' 8., long. 

 151° 49' E. (Station 181). 



This I know only from two or three imperfectly observed specimens, but the 

 characters are so well marked as to leave no doubt of its specific distinctness. 



5. Saphirina opalina, Dana (PI. XLIX. figs. 3-6). 



Saphirina opalina, Dana, Crust. L T . S. Expl. Exped. (1852), p. 1254, pi. lxxxviii. fig. 4. 

 ,, tlwmsoni, Lubbock, Trans. Linn. Soc, vol. xxiii. p. 186, pi. xxix. fig. 22, 23. 



Female. — Anterior antennae five-jointed, clothed with very short setae ; terminal 

 claw of posterior antenna suddenly much narrower than the joint to which it is attached. 

 Abdomen short and broad, five-jointed, all the joints of about equal length, first and last 

 narrower than the rest, second, third, and fourth, strongly lunated, with acute tips. 

 Caudal lamellae subquadrangular, about as long as broad, internal apical angle produced 

 into a large triangular spine, distal margin three or four times sinuated, with sharp points 

 of separation. Inner branch of the fourth pair of feet half as long as the outer branch. 



Habitat.- — Both specimens figured in the plate were taken amongst the Philippine 

 Islands ; Professor Dana's and Sir John Lubbock's were from the tropical Atlantic. 



Judging from the peculiarities of the posterior antennae and caudal lamellae, there can 

 be no doubt that both the figured specimens belong to the same species ; but in the 

 very imperfect separation of the joints of the antennae and limbs in the smaller 

 specimen, the imperfect subdivision of the first cephalothoracic segment, and still 

 more in the presence of only four (instead of five) abdominal rings, I am disj)osed to think 

 we have indications of an earlier stage of growth. It is probable also that the example 

 described by Dana — having the body composed only of eight joints — was not fully grown. 

 The thorax of the larger specimen was lost in the process of dissection, and thus 

 escaped observation, and the caudal setae were broken or imperfect. 



The antennae and abdomen, figured at 4 a and 5 a, seem to be those of a male opalina , 

 and belong to a specimen taken in the same locality as the rest. If the antenna be not 

 malformed, it is a very peculiar one; the difference of the abdominal segments may also 

 be a sexual one. 



