316 J. W. KIKKALDY. 



3. Heteropleuron cultellum, PI. 34, fig. 2. 



Epigonicthys cultelltjs, Peters. * Mouatsbericht der k. Preuss. 



Akad. der Wiss.,' Berlin, 

 1876, p. 323. 

 Branciiiostoma cultellum, Giintlier. 'Report Zool. Coll. H.M.S. 



"Alert,'"1884, p. 32. 

 J, „ Willey. 'Quart. Jouru. Micros. Sci.,' 



vol. XXXV, 1891, p. 361. 



Myotomes, maximum number 56, minimum number 50, 

 usual number 52. 



Myotome formula 32, 10, 10; 32, 12, 8; 33, 10, 10; 34, 

 11, 10; 32, 10, 10 (usual number in thirty specimens). 



Dorsal fin of great height, especially in the anterior region, 

 where it is more than one third of the total height from fin 

 crest to metapleur edge. The rostral fin is short and deep, 

 and is not marked off by a notch from the dorsal fin. The 

 ventral fin presents fin-ray chambers, which do not, however, 

 ever contain fin-rays, either single or double. (Willey first 

 observed this, and I can confirm him.) 



The caudal fin is lancet-shaped, but not strongly marked. 



The oral sphincter underlies the angle of myotome 6; there 

 are sixteen intra-buccal cirrhi. The prseoral tentacles are from 

 forty- one to forty-three in number (in the specimens examined). 

 The notochord is slightly depressed in the rostral region, and, 

 instead of tapering to its anterior extremity, is expanded to 

 form a club-like termination. Posteriorly the notochord pro- 

 jects beyond the last myotome more than it does in other 

 species of Heteropleuron or Amphioxus, and terminates 

 bluntly. The gonad pouches are from seventeen to twenty 

 in number, forming a series on the right epipleur. The 

 maximum length shown by specimens in Haddon^s collection 

 was 3-5 cm. (Willey). 



Distribution. — Torres Straits, Australia. 



Remarks. — This species differs more from the other species 

 of Heteropleuron than any of them do from one another, and 

 differs in features which remove it further than they are from 



