468 THE VOYAGE OF H.M.S. CHALLENGER. 



Hebrides; China Seas; near Station 270, lat. 2° 34' K, long. 149° 9' W. ; Tahiti; 

 Hawaii. 



A specimen much resembling that represented in fig. 4, PI. LXXXIL, but little 

 more than half its length, and with the anterior tooth broad and rounded instead of 

 being sharp, was taken on the passage from the Admiralty Islands to Japan. 



The anterior five somites of the pleon are dorsally smooth, and there exists a tooth- 

 like projection on the inferodateral margin, such as is figured in the female of Lucifer 

 typus, and in the young of some species. 



The sixth somite is not quite so long as the two preceding ; the dorsal surface is 

 furnished with a small sharp tooth at the posterior extremity, and the inferior margin 

 is armed near the posterior extremity with a minute sharp tooth, just in front of which 

 is an obtusely pointed lobe. 



The telson is long, slender, about half the length of the sixth somite, forked at the 

 extremity and armed on each side with a small sharp spine. 



The ophthalmopoda are pyriform, stout, and about half as long as the antennal somite. 



First pair of antennas has the first joint of the peduncle subequal in length to the 

 opthalmopoda ; the second and third joints are short and subequal ; the flagella are 

 broken off. 



The second pair of antennas carries a long, slender scaphocerite, which terminates 

 subapically in a sharp point, and is subequal in length to the first joint of the peduncle 

 of the first pair ; the terminal joint of the peduncle is about half the length of the 

 ophthalmopoda ; the flagellum is wanting. 



The gnathopoda possess the normal character as in the adult type of the genus. 



The pereiopoda are broken off at the distal extremity of the carpos, except one of 

 the posterior pair, which shows the existence of the minute dactylos which makes an 

 imperfect chela. 



The pleopoda are long, slender, and decrease in length posteriorly. 



The plates of the posterior pair are unequal, the inner not being longer than the 

 telson, and the outer being one-third longer and laterally armed with a tooth near 

 the distal extremity, which is broad and fringed with hairs. 



Length, 4 mm. (0"16 in.). 



Observations. — The general distinction of this specimen from most others lies in its 

 robust appearance, particularly of the antennal somite, or that portion that separates the 

 antennas from the oral region. This is, however, a feature attributable to an immature 

 condition, as may be seen in those stages, as in Sceletina, where the antennal region is 

 not distinctly separated from the oral and gastric. 



On the sixth somite of the pleon, the lobe anterior to the small sharp tooth may be, 



