80 MR. T. SCOTT ON ENTOMOSTRACA 



About twenty specimens of this species were obtained in tow-nettings from the 

 localities described ; tlie specimens were all more or less imperfect, especially tbe 

 anterior antennae and swimming-feet. 



The specific name has reference to Mayuraba, a place on the coast near Station 23, 

 one of the two localities where the species was obtained. 



Genus Mectnoceba, I. C. Thompson (1888). 

 1888. Mecynocera, I. C. Thompson, Jouru. Liun. Soc. (Zoology) vol. xx. p. 146. 



Mectnocera clatjsii, I. C. Thompson. (PI. I. figs. 27-3i ; PI. II. 7-10.) 



1888. Mecynocera clausii, I. C. Thompson, Jouni. Linn. Soc. (Zoology) vol. xx. p. 140, pi. xi. 

 figs. 1-4. 



Length fully 1 mm. Female somewhat longer than the male. Body elongate, 

 slender. Cephalothorax composed of six segments ; viewed dorsally the first is almost 

 cylindrical ; forehead somewhat angularly rounded ; the postero-lateral angles of the 

 last segment are rounded. Anterior antennae fully twice the length of the animal, 

 slender, 2i-jointcd ; the Kith to the 20th joints are considerably longer than any of the 

 others ; several of the middle joints of both antennce in male and female are provided 

 with longitudinal rows of small spiniform teeth ; two, or even three, rows were observed 

 on some of the joints, on others only one row ; the antenna; are sparingly setiferous 

 (PI. I. fig. 31). The annexed formula shows the proportional lengths of the joints : — 



7 . 14 . 7 . 7 . 7 . 7 . 7 . 12 . 12 . 10 . 12 . 13 . 14 . 17 . 18 . 22 . 2 4 . 29 . 26 . 24 . 18 . 12 . 8 .14 

 1 2 3 4 .5 6 7 S 9 10 11 12 13 14 15~10 17 18 19 20 21 22 23 24" 



The basal joint of the posterior antennoe stout, primary branch 2-jointed (exclusive of 

 the basal joint), the first being nearly a third longer than the other; secondary branch 

 7-jointed ; the second joint is longer than the first, and nearly equal to the entire length 

 of the next four ; the tliird to the last joints very short (PI. I. fig. 30). Mandible-palp 

 well developed, 2-branched, basal part stout, distally narrowed and jiroduced to form 

 the base of the 1-jointed branch ; the second branch, which occupies a submarginal 

 position, is ^-jointed (PL II. fig. 7). Poot-jaws and swimming-feet nearly as in 

 RJdncalanus, except that the inner branches of the first swimming-feet are 1-joiuted, 

 the inner branches of the second, third, and fourth pairs are 3-jointed ; the exterior 

 distal angles of the joints of the outer branches are armed with short stout spines which 

 are curved inwardly ; the last joint of the outer branches of the fourth paix has a similar 

 spine on the exterior margin (PL I. fig. 33) ; the outer branches of all the first four 

 pairs possess long delicate terminal spines. Tlie fifth ])My are 1-branched, alike on both 

 sides and in both sexes ; basal portion 2-jointed, not much stouter than the terminal 

 portion, which is 3-jointed. There is, so far as could be observed, no terminal spine. 

 Caudal stylets somewhat divergent, and about two thirds the length of the last abdominal 

 segment ; caudal setae four, long, plumose. 



Habitat. Station 2, 25 fathoms, collected January 1st. Lat. 6" 31' N., long. 12' 39' W., 

 surface, collected January Gth. Lat. 1. 31' G" N., long. & H 4" W., 50 fathoms, collected 





