DECAPODS 



97 



Owen, the rostrum is longer and narrower than in S. affinis, extending to 

 the extremity of the superior antennae; the dental formula was the 

 same, -^, in the 3 specimens preserved. According to Owen's figure, 

 the antennular peduncle extends about to the middle of the rostrum, the 

 second and third segments are subequal, the thickened portion of the 

 outer flagellum is shorter than the peduncle. The rostrum curves strongly 

 upward in its anterior half. 



SPIRONTOCARIS BIUNGUIS Rathbun. 

 Spirontocaris biunguis RATHBUN, Proc. U. S. Nat. Mus., xxiv, 899, 1902. 



This species of the gaimardii group is an inhabitant of deeper water, 

 and is distinguished by its larger eyes, longer rostrum, subchelate dactyli, 

 and by having an exopod and an epipod on the outer maxilliped, while 

 the pereiopods are destitute of epipods. 



Carapace carinated on its anterior half or two thirds. Rostrum from one 

 and a fourth to one and two thirds times as long as remainder of cara- 

 pace, its poste- 

 rior half or third 

 gradually as- V 

 cending, the re- 

 mainder more 

 abruptly so ; up- 

 per limb narrow, 

 the widest point 

 in front of the 



FIG. 44. Spirontacaris biunguis. Station 3324. a. Side. 



eye; lower limb 9 (Xi^). 6. Dorsal view of anterior portion. ?(Xi). c. 

 , Dactylus of one of last 3 pairs of legs (X 10). 



a little wider than 



the upper ; terminal third a slender sharp spine, not limbed ; 

 dorsal spines 5 to 7 (two on carapace), ventral spines 4 to 7. 

 Antennal spine strong ; pterygostomian spine or tooth very small. 



Eyes very large and oblique, pyriform, the cornea covering the greater 

 part of the peduncle. Antennular peduncle extending a little past the 

 middle of the antennal scale ; second joint three times as long as third ; 

 outer scale reaching to end of first segment ; thickened portion of outer 

 flagellum extending in the female one third, in the male two thirds of its 

 length beyond antennal scale. This last is four fifths as long as carapace ; 

 antennal peduncle reaching end of second segment of antennular 

 peduncle ; flagellum longer than the body. 



The tips of the maxillipeds are half way between the antennal peduncle 

 and the tip of the scale. The first pair of feet attain the middle of the 

 last joint of the antennal peduncle ; the palm is less than twice as long as 



