666 CRUSTACEA. 



Plate 44, fig. 7 a, animal, enlarged ; b, dorsal view of thorax ; c, 

 caudal extremity ; d, palpus of legs. 



Sooloo Sea, southwest of Panay. Collected, January 29, 1842. 



Length, one-fourth of an inch. Colourless. 



This species has smaller eyes and beak, and narrower front, with 

 less divergent angles than the armata. The breadth of the front of the 

 carapax is about half its greatest breadth. The beak is very slender, 

 but does not project beyond the eyes when they are extended forward. 



Genus RACHITIA. 



Carapax rostratus. Oculi oblongi, obconici. Antennas internee nan 

 bifida?, flagello tenui confectce. Antennce secundce bifidce, laminti basali 

 non instructor. Segmentum abdominis sextum valde elo?igatum, septi- 

 mum postice valde latins et bilobatum, rotundatum et sehdis longius- 

 culis inwquis instructum. 



Carapax rostrate. Eyes oblong, obconical. Inner antennae not bifid, 

 ending in a slender flagellum. Outer pair bifid, and without a 

 basal scale. Sixth abdominal segment much elongate; last much 

 broader behind and bilobate, lobes rounded, and set with loutish 

 unequal setae. 



The animal upon which this genus is founded is not mature, and we 

 cannot feel certain that it is not the young of some Decapod, possibly 

 one of the subfamily Oplophorinae, family Palaemonidae. Yet it so 

 nearly approaches a tMetina in its trident front, its obconical ' eyes 

 and its antennae, both first and second pairs, that we are inclined to 

 refer it to the same family with that genus. Moreover, it seems im- 

 probable that the caudal segment of ftachitia could belong to any of 

 the Palsemonida, The abdomen of the only species known has along 

 the back a long spine to each segment, except the two last, and the 

 sixth segment is as long as the four preceding. The caudal extremity 

 is evidently immature; the caudal lamella are quite small The 

 thoracic legs are only partly developed. Only three pairs were jointed, 

 these were bifid, and the outer branch corresponding to the palpus wa 

 multiarticulate. The abdominal legs were altogether wanting 



