CEI'HALOCHOKDA. 2 I '. 



remaining 18 (fig. 6) the anterior end of the dorsal fin is much further behind the 

 anterior end of the notochord. The relation of these two structures to one another 

 is evidently susceptible of some variation. This receives support from what we know- 

 in another species. In Asymmetron lucayanum , from the Maldive Archipelago, 

 FOKSTER-COOPBR (8) has figured the dorsal fin and notochord as ending almost 

 conterminously at the anterior end, while in Andrews' original figure (3) and in 

 Kirkaldy's figure (6) of that species the anterior end of the notochord is far in front 

 of that of the dorsal fin. 



In one or two specimens 1 was able to count the oral cirri. They vary from 26 to 

 32 in number. The intertentacular membrane between the oral cirri of this species 

 is much deeper than is seen in B laneeolatum, var. belcheri, and extends from 

 one-third to half the way up. The sensoiy-papiike, on the other hand, are much less 

 marked. In one preparation of the oral cirri of this species one cirrus was seen to 

 be branched about one-third of the way up, and the branch was about half as long as 

 the cirrus. 



In No. XIII. , Table III., a curious structure (fig. 7) was noticed in the dorsal fin 

 just behind the level of the mouth. At this place a break in the fin occurs. A slit 

 runs downwards and backwards for about the length of 2 myotomes. The slit is 

 lined throughout by the epithelium that covers the rest of the body. Posterior to 

 the slit, and continuous with it, is a darker stretch of tissue which looks like a closure 

 of a former extension of the slit. Sections do not show much more, but the structure 

 seems to be confined to the dorsal fin. The nervous system, notochord, and other 

 neighbouring organs are quite unaffected. It is probably the result of some accident 

 arresting the growth of the fin at this spot during its development. 



Asymmetron cultellum (Peters). Plate I., figs. 8-10. 



Epigonichthys cultellus, Peters, 1876; Gill, 1895; Willey, 1901. 

 Branchiostoma cultellum, Gunther, 1881; and Willey, 1891. 

 Heteropleuron cultellum, KlRKALDY, 1895. 



Only two specimens of this interesting species were present in the collection, one 

 from near the coral reefs off Vangali (Stn. Lib), March 5th, in 3 fathoms, and the 

 other from the East Cheval (Stn. XL), February 4th, in 6 fathoms. They were 

 both quite .small, one measuring 23 millims. and the other 25 millims. Both had 

 well-developed gonads, one being a male (the smaller of the two), and the other a 

 female. 



It is evident, therefore, that this species, like A. cingalense, is a small one as 

 compared with B. laneeolatum and its variety beleheri. 



The male had 17 gonads and the female 20 gonads, both on the right side. The 

 myotome formula for the male specimen was 35, 12, 7 total, 54 ; while that of the 



2 v 2 



