CEPHALOCHORDA. 221 



The food nt' these tropical forms appears to consist largely of diatoms, especially of 

 forms found growing over zoophytes, corals, shells, and other submarine objects. In 

 nearly all, the alimentary canal was seen to contain the skeletons of such forms, and 

 fsecal pellets showed the same. 



The tables at the end of the report show how extremely variable the species of the 

 group are, and the more extended our knowledge of this group becomes, the less 

 distinctly do the species appear to be separated. The spawning time of the group In 

 tropical seas appears to be the latter half of March, rather earlier in the year than in 

 more temperate seas. 



B. lanceolatum is recorded from the Indian < >cean for the first time. It appears to 

 be a cosmopolitan species, being by far the most widely distributed of all the species. 

 The tropical forms differ but slightly from their Mediterranean relations. 



The variety (as I consider it) B. belcheri is the predominant form in these waters. 

 and constitutes 60 per cent, of the present collection. 



A. cingalense, as might be expected, is also well represented in the collection. 



The fact that only two specimens of .-J. cultellitm were found, suggests that Ceylon 

 may be nearly at the limit of its distribution, and that it becomes more numerous as 

 we approach Australia. 



The re-discovery of B. indicum is interesting, and extends somewhat its known 

 distribution. 



Perhaps the most interesting specimens of the collection were those I have referred 

 to B. pehxgicum, and it is to be regretted that their state of preservation did not 

 admit of a more complete study of their anatomy, which would probably show points 

 of interest. The collection demonstrated, however, definitely, that this species is 

 truly pelagic. 



The most surprising find is B. californiense, which, though showing some slight 

 variation, is in most respects the same as its American relations. 



Finally, this tropical part of the Indian Ocean seems to be either the home of this 

 group, or is exceedingly well populated, as no less than eight out of the eleven well 

 characterised species have now been recorded from the seas around Ceylon, as 

 follows : - 



Branchiostuma lanceolatum 



I Mtto, var. belcheri 



,-, , r (Herdmajst), 



Ceylon I x 



L (Andrews ?) 



CeyloD (Hebdman), 



Singapore (Bedford). 



,. , , , [ Orissa Coast of India . . (Willey), 



rfranchiostoma indicum . { 



I Ceylon (Hkrdman) 



,, , , , I Indian Ocean (GARDINER) 



Uiulf of Manaar .... (Herdman) 



