16 



EDGAR R. WAITE 



a low ridge which extends to below the base of the eighth-ninth dorsal rays ; the 

 pores reappear faintly in the mid line above the fifth anal ray, are nineteen in 

 number, and do not quite reach the base of the caudal rays. 



Colours. The single specimen preserved is almost colourless, but bears traces of 

 darker markings across the back, and spots on the outer caudal rays. 



Length of specimen, 146 mm. It was taken in company with examples of 

 Trematomus bernacchii in August 1908, off Cape Royds, at a depth of thirty to eighty 

 fathoms. 



The most apparent difference between A. shackletoni and the other members of 

 the genus is in the larger number of spines and rays in the dorsal and anal fins, the 

 dorsal spines in the other species being but three in number ; some systematists 

 would probably regard the distinction as of generic import. 



In other respects the three species are very similar, A. shackletoni being in some 

 characters intermediate. By comparison with Lonnberg's figures,* it is found to 

 resemble A. skottsbergi in general form, but otherwise more nearly approaches 

 A. minis, agreeing in the protuberant eye, the high second dorsal fin, and possibly 

 also the coloration. 



The comparative proportions of the three species are shown below : 



Lonnberg, loc. cit., Plate IV,, Figs. 14 [A. mirus) and 15 (A. skottsbergi). 



