398 EEV. T. K. K. STEBBING ON AMPHIPODA FEOM 



10. 



11. 



-Second giiathopods of tlie male, fiftli joint not produced between 



the fourth and the sixtli 10. Hyale Rathke, 1837. 



Second gnathopods of the male, fifth joint produced between the 

 fourth and the sixth, 11. 



f Telson undivided 11. ffyafeWa S. I. Smith, 1875. 



L Telsou more or less divided 12. ^//orc/tes/es Dana, 1849. 



Talokchestia tridentata, u. sp. (Plate 30 B.) 



The back is not very broad. The first four pairs of side-plates are scabrous, tlie first 

 shallower than the three following ; the fifth is the widest. The eyes are roughly oval, 

 rather more than their longer diameter apart. 



First antennce. Very small, not reaching the middle of the penultimate joint of the 

 peduncle of the second antennre. 



Second antennce. About one-third as long as the body ; the last joint of the peduncle 

 twice as long as the penultimate ; the flagellum scarcely as long as the peduncle, flattened, 

 slightly tapering, consisting of about twenty-four sliort transverse joints. 



First gnathopods. Spinose, the fifth joint long, the subapical pellucid process of the hind 

 margin narrow, very prominent; the sixth joint much shorter, rather narrow, the apical 

 pellucid process prominent, the finger with sinuous inner margin, extending beyond the 

 apical process of the sixth joint. 



Second gnathopods. The second joint is channelled in front, the apices of the front 

 margins being faintly lobed ; the third joint is rather larger than the fourth, neither of 

 them longer than broad; the fifth joint is exceedingly diminutive ; the sixth very large, 

 its hind margin fringed with spiniiles, the palm oblique, having near the finger-hinge a 

 large triaugvdar spinulose tooth, followed by a sinuous slope, and defined from the hind 

 margin by two tf elh side by side, only one of them being visible in a profile view ; the 

 finger very large, with swelling of the inner margin near the hinge ; the rest of the 

 margin concave, fringed with small spinules. 



Second j^erceopods. This pan* is much shorter than the first. The finger has a strong 

 prominence near the base of the nail. 



Third per (eo2)ods. This pau" is very short, the second joint nearly as broad as long. 



Fourth and fifth per cEopods. These pairs are not very elongate, but much longer than 

 the third pair. All the perajopods are spinose, with rather small branchial vesicles. 



First nropods. Long, the rami much shorter than the peduncle, both carrying- 

 marginal spines. 



Second nropods. The rami are not shorter than the peduncle, with stout spines. 



Third urop)ods. The ramus is at least as long as the peduncle. 



Telson. Sliort, spinulose. 



Length. Less than half an inch, 11 mm. 



Hab. California. The specimen described, a male, was sent me by S. J. Holmes, Esq., 

 among specimens of Orchestia traskiana. 



Without knowledge of the other sex this species can only conjecturaUy be assigned to 



