NO. 2286. THE NEW COPEPOD FAMILY SPHYRIIDAE—WILSOX. 585 



the back of the head protrude much more than in houvieri, the 

 maxillipeds are considerably longer^ while the spines at the poste- 

 rior end of the body are shorter and smaller. When taken in con- 

 nection with the differences in the details of the appendages these 

 characters serve to establish the species. The single specimen 

 obtained does not necessarily mean that the species is scarce, because 

 its host is a deep-sea fish, and not many specimens have been examined 

 for parasites. 



REBELULA GRACILIS, new species. 



Plate 53, fig. 33; plate 54, fig. 45. 



Host and record of specimens. — Two females, one with egg strings 

 and the other without, were obtained by the Bureau, of Fisheries 

 steamer AWatross oil Marthas Vineyard in 1882 from Synapho- 

 hranchus pinnatus. The first of these is made the type of the new 

 species with Cat. No. 49754. U.S.N.M. ; the other becomes a para- 

 type, Avitli Cat. No. 49755, U.S.N.M. Another species without egg 

 strings was obtained off New Jersey by the Bureau of Fisheries 

 steamer Albatross in 1884 from Histiohranchus infernalis, and has 

 been given Cat. No. 49756, U.S.N.M. A fourth specimen, also with- 

 out egg strings, was obtained at the same time and place from 

 Synaphohranchus pinnatiis, and was numbered 6126, U.S.N.M. 



Specific characters of female. — Cephalotliorax nar]-ow and from 10 

 to 15 times as long as wide, transversely wrinkled posteriorly but 

 smooth anteriorly, the smooth part considerably wider than the 

 wrinkled portion, which passes insensibly into the chitinous neck. 

 Head separated from the rest of the cephalothorax by a deep groove, 

 as in ed'warclsH; neck very slender anteriorly, bent and tv\'isted in 

 different directions, considerably thickened, and straight posteriorly. 

 It is armed on the slender portion, about one-third of its length 

 from the anterior end, with several irregular chitin knobs, whose 

 combined diameter is not more than three times that of the neck 

 itself. The nec^k joins the anterior end of the genital segment, 

 usually at an obtuse angle with the dorsal surface of the latter. 

 Trunk comparatively large and thick, obcordate, but much wider 

 anteriorly than in cornuta, namely, three-fourths as wide and half 

 as thick as long. The pits on the dorsal and ventral surfaces are 

 but little sunlcen in any of the specimens and their edges usually 

 protrude a little. 



The lateral posterior lobes are practically lost in the general con- 

 tour of the trunk; the genital processes are small and spherical. The 

 posterior processes are a little more than half the length of the trunk 

 and are covered with elongated cones, which are enlarged but not 

 divided at their tips, and are all about the same length. The egg 

 strings are as long as the entire body, but much narrower than in 

 houvieri; the width less than one- twentieth of the length. 



