1 



928 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



The first perseopods are rather longer than the second. The latter 

 have, as usual, the small finger notched on the inner margin near the 

 apex. The fourth and fifth pora^opods are much longer than the third. 

 The second joint in the fifth paii- is much broader than that in the 

 fourtli, being about as broad as it is long. 



The hind corners of the second and third pleon segments are quad- 

 rate. The first uropods have equal rami, nearh" as long as the pedun- 

 cle. The second pair are shorter, with the rami equal and as long as 

 the peduncle, the inner ramus so placed as not to reach quite so far 

 back as the outer. The slender ramus of the third pair carries a row 

 of four little spines. It is shorter than the stout peduncle. The sixth 

 pleon segment is dorsally incomplete, having the gap in its armour 

 cloaked by the tclson. The telson has a dividing line down the center, 

 the apex being bilobed, carrying two or three spinules on each lobe, 

 and a pair of sublateral spines is placed higher up. 



The male specimen, of which the parts are figured in the accompany- 

 ing plate, measured from front of head to end of uropods seven- 

 twentieths of an inch, while a male with notch in palm of second 

 gnathopods still undeveloped was onlv four-twentieths of an inch long, 

 or 5 mm, as contrasted with about 9 mm, in the larger (^xample. 



The specimens were forwarded to me as having been taken in Jan- 

 uiiry, 1902, by Mr. P. BioUey, at Isla del Coco, otf Costa Rica. 



The specific name is chosen to direct attention to the points of com- 

 parison between this form and that which for the present should be 

 known as Orchestla tucm'mma Fritz Miiller. 



HYALELLA FAXONI, new species. 

 Plate LXi: 



The back is well rounded, devoid of teetli. The first three segments 

 of the pleon have the postero-lateral angles acute, those of the first 

 pair being scarcely, but those of the third conspicuously, produced. 



The eyes are round, ver}^ small, and wide apart. 



The first antennae have the peduncle well developed, but with the 

 third joint a little shorter than the second, and the second than the 

 first. The flagellum is elongate, its joints attaining to fourteen in 

 number in the male. A specimen in which the flagellum was eleven- 

 jointed had the eleventh joint about level with the eighth joint of the 

 flagellum of the lower antenna\ 



The second antennae have both peduncle and flagellum longer than 

 those of the preceding pair, the terminal joint of the peduncle consid- 

 erably longer than the penultimate in the male, l)ut very little longer 

 in the female, an unbroken flagellum in the male having as many as 

 seventeen joints. In a female specimen a flagellum of thirteen joints 

 answers to one of ten in the first pair. 



