1484 THE VOYAGE OF H.M.S. CHALLENGER. 



Fourth Perseopods. — The large first joint more than twice as long as the remaining 

 joints together ; the third joint much longer than the three following joints together 

 pectinate along the front margin with retro verted teeth, the apex produced half way 

 alono- the fourth joint ; the somewhat crooked finger is nearly half the length of the fifth 

 joint. 



Fifth Perseopods. — The first joint transparent, two or three times as long as broad, a 

 little curved, the apex divided, the hinder division produced a little below the front. 

 There is no trace of any other joints. 



Uropods. —Peduncles of the third pair much shorter than the rami ; the outer ramus 

 nearly equal in length to the inner, its outer margin nearly smooth, the inner finely 

 pectinate ; the inner ramus quite distinct from the peduncle, much of each margin finely 

 pectinate. 



Telson coalesced with the preceding segment, longer than broad, triangular, the 

 narrowly rounded apex extending just beyond the apices of the third uropods, the sides 

 slightly concave above and below. 



Length about one-fifth of an inch when fully extended. 



Locality. — September 13, 1874, Arafura Sea; lat. 8° 18' S., long. 135° 7'E. ; surface ; 

 surface temperature, 79°. Three specimens, two of them, perhaps all three, males. 



Remark. — The specific name is taken from the place of capture. 



Tetrathynts forcipatus, Claus. 



1879. Tetrathi/rus forcipatus, Claus, Die Gattungen imd Arten der Platysceliden, p. 14 



1887. „ „ Bovallius, Systematical List of Amph. Hyper., Bihang till K. 



Svensk. Vetensk.-Akad. Handl., Bd. 11, No. 16, p. 47. 

 1887. „ „ Claus, Die Platysceliden, p. 40, Taf. v. figs. 10-18, Taf. vi. figs. 1-3. 



The rostral triangle conspicuously produced, the lower margin of the head forming 

 an acute angle on either side of it. 



Eyes. — One division large, with large pigment, this pair occupying almost all the 

 sides and top of the head ; the other division very small, with small radiating ocelli, not 

 set closely together, this pair placed in the front of the head on either side of the rostral 

 triangle. 



Fourth Perseopods. — The third joint with its front apex more produced, and produced 

 more sharply than in Tetrathyrus moncccuri, this and the two following joints being 

 relatively narrower and shorter than in that species, but similarly pectinate, the finger 

 small. 



Fifth Perseopods. — The first joint drawn out to a very narrow apex, perhaps tipped 

 with a minute second joint. 



