A NEW SPECIES OF ASYMMEIRON. 



I. — Introduction. 



The Commonwealth F.I.S. "Endeavour," whilst conducting 

 Its operations along the southern coast of Australia, secured 

 specimens of the well-known Asymmetron bassanum, and also 

 of another species of the same genus which, on examination, 

 proves to be a new one. The Department of Trade and Cus- 

 toms, to whom the material secured by the "Endeavour" 

 belongs placed these specimens in the hands of Professor W. 

 Baldwin Spencer for identification and description, and at his 

 request 1 have undertaken the work. 



Asymryietron hasscuiuiii is not uncommonly met \yith at 

 depths of about twenty fathoms off the \'ictorian coast in Bass 

 Strait and in Western Port in four fathoms. Specimens were 

 secured bv the "Endeavour" on the east side of Flinders 

 Island, to' the south of St. Francis Island in the Australian 

 Bight, and also off Shoalhaven on the New South Wales 

 -coast.' It has not hitherto been met with to the west of Bass 

 Strait. . 



The new species was dredged at a depth of thirty-hve 

 fathoms on the south side of^St. Francis Island in the Aus- 

 tralian Bight in company with A. bassanum, from which it, 

 however, is quite distinct. In the following account a des- 

 •cription is given of its more important features. 



II. Description of the Species. 



Asymmetron australis, sp. nov. 

 (Plate xxxvii., figs. 1-7.) 



The averaoe length of twelve specimens is 26 mm. ; the 

 average number of myotomes, 55; the average myotome 

 formula, 33, 9, 13- 



The rosiraJ fin is slightly raised above the dorsal fin, and is 

 rounded anteriorlv. The anterior end of the notochord is 

 inclined a little upwards in the rostral fin (PI. xxxvii., fig. i). 



There are 25-33 oral cirri bearing sense papillae, arranged 

 in a single series and united together by a web. They are 

 disposed at about equal intervals to the right and left of a 

 median ventral one, as shown in PI. xxxvii., figs. 3, 4 and 5. 

 The web is continuous all along, and is highest in the mid- 

 ventral portion, becoming lower anteriorly on each side. In 

 PI. xxxvii., fig. 6, there is a small basal portion only, in the 

 mid line, but t'his, I think, must be the result either of injury 

 :or arrest of growth, for new tentacles do not develop in between 



