REPORT ON THE AMPHIPODA. 1483 



smooth except for one or two indents ; peduncles of the third pair longer than the 

 outer ramus, a little shorter than the inner, which is distinguished from the peduncle 

 hy an indent on the inner margin and a suture of the under surface ; the rami ornamented 

 like the preceding pair, but respectively much smaller. 



Telson coalesced with the preceding segment, though the lateral margins of the 

 two are not continuous ; the breadth of the telson at what seems to be its proper base 

 being less than the length ; the apex narrow, somewhat rounded, not reaching so far as 

 the apex of the inner rami of the third or of the first uropods ; there are a few little 

 setules about the apex and two or three on each lateral margin. 



Length. — One-fifth of an inch. 



Localities. — Station 162, April 2, 1874; off East Moncceur Island, Bass Strait; lat. 

 39° 10' 30" S., long. 146° 37' 0" E.; surface; surface temperature, 63 c, 2. Several 

 specimens. 



Station 164a, June 13, 1874; east of Australia; lat. 34° 9' S., long. 151° 55' E.; 

 surface to 50 fathoms ; surface temperature, 70° '2. One specimen. 



Remarks. — The specific name refers to the place of capture. In Tetrathyrus 

 rectangular is, Bovallius, from the Indian Ocean, the last joint of the lower antennae is 

 less than half as long as the preceding joint, the finger in the gnathopods is more than a 

 third of the length of the hand, and the fourth perseopods are said to be without finger. . 



Tetrathyrus arafurse, n. sp. 



In general appearance and in respect to the antennae and mouth organs so far as 

 examined this species agrees substantially with Tetrathyrus moncosuri. 



First Gnathopods. — The third joint much wider than the wrist, so as to project 

 beyond it both before and behind, having one spinule at the flattened apex of the front 

 margin and four spinules on the hind margin ; the wrist oval, the front margin smooth, 

 the hinder with four spinules. 



Second Gnathopods. — The third joint much longer as well as broader than the wrist, 

 with two sj)inules on the front apex and seven along the hinder margin and its apex ; 

 the wrist also with seven spinules along its convex hind margin. 



First and Second Perseopods very long and slender, more conspicuously so than in 

 the other two species here described. 



Third Perasopods. — First joint a long oval, nearly equal in length to all the remaining 

 joints together, the front margin sinuous with some minute spinules, the smoothly convex 

 hind margin interrupted just before the broad apex of the joint is reached, the short 

 second joint partially overlapping the small emargination thus formed ; the third joint 

 about as long as the fifth, much shorter than the fourth. 



