REPORT ON THE CRUSTACEA MACRURA. 745 



carina, commencing with the anterior margin of the somite, being continued posteriorly 

 to a tooth that is smaller than the preceding. The fifth and sixth somites resemble the 

 fourth, except that the posterior teeth are successively smaller. 



The telson is slightly carinated anteriorly, flattened posteriorly, and terminates in 

 four small spines ; it is laterally depressed and furnished with three or four almost 

 rudimentary spinules. 



The first pair of antennas is subequal in length with the rostrum, and the upper 

 flagellum carries on the under surface a thick mat of membranous cilia. 



The second pair is slender and almost equal in length to the animal. 



All the other parts appear to possess only generic characters. 



Observations. — After having had the opportunity of examining the specimens in the 

 possession of Professor Alphonse Milne-Edwards, I felt convinced that those procured by 

 Professor Agassiz, off St. Lucia, in the West Indies, at a depth of 422 fathoms, were 

 specifically the same as that taken by the Challenger in the Polynesian Archipelago at 

 200 fathoms ; although the localities are distant, the variations between them are few and 

 unimportant. 



The type has the rostrum subequal in length with the carapace and gradually curves 

 upwards from the base, the solitary tooth upon the lower margin being nearly on a 

 level with the distal extremity of the scaphocerite. 



The Challenger specimen has the rostrum rather shorter than the carapace, slightly 

 curving upwards from the horizontal until the solitary tooth is reached, whence the 

 direction is upwards and forwards, the apex being somewhat depressed. The five small 

 teeth on the dorsal crest increase gradually in size from the posterior to the anterior, 

 forming part of a carina, which commences on the cardiac region. 



Acanthephyra acanthitelsonis, n. sp. (PI. CXXV. fig. 3). 



Carapace smooth, dorsum slightly elevated posteriorly. Rostrum slender, horizontal, 

 armed on the upper surface with seven or eight small teeth and with four or five on the 

 lower, and a small fasciculus of ciliated hairs at the base. 



Pleon smooth, laterally compressed, and dorsally carinated in all except the first 

 somite, which is smooth and posteriorly notched in the median line, as is also the 

 second, whereas the third and succeeding somites are posteriorly produced to a sma 

 overlapping tooth, of which that on the third somite is the largest. 



Telson longer than the outer plates of the rhipidura, slender, armed with about forty 

 strong articulating spines, twenty on each side, and terminating in two smaller ones at 

 the extremity. 



The first pair of antennas is about two-thirds the length of the animal. 



(ZOOL. CHALL. EXP. PART LII. — 1887.) Fff 94 



