of the Lnrvm of Marine Animals. 409 



Generally my stock died off in 4 or 5 days, an occurrence 

 ascribed at the time to wrong and insufficient food,&c. Un- 

 fortunately I could not carry the experiments very far ; but 

 the larvae of one molluscan, given to me by Signor Lo Bianco, 

 began to show decided changes to veligers after their third 

 night as trochosplieres, i. e. 70 to 80 hours ; but this, I 

 fancy, is altogether exceptional. At the previously cited 

 localities I found no such larvse (nor veligers), though they 

 were numerous and increasingly common as one beat up for 

 the last 150 miles from Kotuma to Fiji. I obtained, bow- 

 ever, off Rotuma a number of specimens of what appeared to 

 be a Sipunculid larva, and which must have come from Fiji 

 or from deep-sea parentage. 



I now come to the planula-group of larvae, a group to which 

 the young of most Coelenterates belong, as well as certain 

 sponges, Turbellaria, &c. My observations in the tropics 

 were carried out mainly in connexion with the distribution of 

 Coelenterates, and particularly of corals. The difficulties on 

 account of size and delicacy are much greater when one sets 

 out to examine a group of larva? such as these ; yet I con- 

 vinced myself that the nets &c. were suitable, and I found at 

 Minikoi practically no difference in depth either by night or 

 day. Actinian larvee, according to my observations at the 

 latter locality, at llotuma, and at Funafuti^ live for seven or 

 eight days as such, but on the fifth day the planulse of several 

 species of corals had settled in the jars kept for the purpose. 

 In none of the localities cited above from which I took 

 plankton did I find any planulae, nor, indeed, did I obtain 

 any at a greater distance than 50 miles away from the nearest 

 reef. In fact, my observations lead me to conclude that in 

 no case could they be directly carried from Ceylon to the 

 Maldives, though it is conceivable that these larvaj might be 

 swept from reef to reef vid the various L:»ccadive banks, and 

 so reach that group. 



I fear, however, that in the present state of our knowledge 

 any consideration of larval distribution is premature and must 

 be inconclusive. I start, perhaps, with a fallacy in assuming 

 that the deep-sea fauna on our ocean routes does not send up 

 larvae to the surface-waters, though the general tendency of 

 its forms appears to me to be to give up larval development 

 or to reduce it as much as possible. I leave out of account 

 the effect on the different forms of the various predatory 

 animals of the plankton, well knowing that my limited 

 observations may be invalidated by the larvae having been 

 preyed on by some particular form abundant at the time. I 

 know that my observations are not sufficiently numerous to 



