FISHES. — MCCULLOCH. 89 



Described from three specimens, 87-80 mm. long from the 

 snout to the end of the tail. The collection includes an excellent 

 series of ninety seven specimens, 42-93 mm. long, which exhibit 

 considerable variation in the form of the post-temporal spines. 



Fig. 4,—Polyipni(s tridentifer. Variation of post-temporal spines. 



Normally there are three spines as described above, but they 

 are often either deformed or not developed, and may be quite 

 different on each side of the same individual as in the accompany- 

 ing figures. The variations are not connected with the age of 

 the specimens, the spines being equally developed in young and 

 old specimens. 



Young specimens are a little deeper than the larger ones, the 

 depth being 1,54 as against 1.75 in the length; the latter 

 measurement is taken from the most elongate specimen of the 

 series. There appears to be but very little variation in the 

 arrangement of the photophores, though those above the anal are 

 a little more uneven in some than in others. In all the remaining 

 characters the specimens are very similar to one another. 



This species is very near to P. spinosus, Gunther 1 but has 

 more dorsal and anal rays and a greater number of anal photo- 

 phores. It is also more elongate, and the post-temporal spines, 

 though variable, are much more developed than in that species! 

 The same differences distinguish it from P. stereope, Jordan & 

 Starks 2 , which also has a smaller eye. It resembles P. nutting!, 

 Gilbert 3 in general form, but has more anal photophores and a 

 different colour-pattern ; in that species also the post-temporal 

 spines are but little developed. P. late mat us, Garman 4 , the 

 only other species, is not a true Polyipnus according to Gilbert 5 , 



Lor.— Great Australian Bight, Long. 129°28'E„ 350-450 

 fathoms: Mav 14. 1913. 



1 Gunther- " Challenger " Rept,, Zool., xxii., 1887, p. 170, pi li fig b 



2 Jordan & Starks— Hull. U.S. Fish. Coram., 1902 (1904), p 581 ' 

 pi. ii., fig. 3. 



3 Gilbert— Bull. U.S. Fish. Coram., 1903 (1905), p. 609, pi. Ixxiii. 



4 Garman— Mem. Mus. Comp. Zool., xxiv., 1899, p. 238. 



5 Gilbert — Lor. cit. p. 610. 



