358 ITS HABITS AND AFFINITIES. 



into my possession ; all of which were dipped from 

 the surface of the sea off the harbour of Ilfracombe, 

 about the end of August. In a glass jar their motions 

 were excessively vivacious; they swam with great 

 swiftness by the rapid vibration of the lateral fins ; 

 so incessantly that it was with the utmost difficulty I 

 could examine them with the microscope. They darted 

 through the water in all directions, across and around 

 the jar; and when they rested, their translucency 

 rendered them almost invisible. They soon died in 

 captivity ; I think I did not keep one of them longer 

 than the second day. 



The form of this animal is so anomalous that it is 

 difficult to assign it a place in the system of nature. 

 At first sight it has somewhat the aspect of a 

 Branchiopod Crustacean; but the evertible oesophagus, 

 the numerous lateral lobes, and the leaf-like expan- 

 sions with which they are terminated, rather indicate 

 an affinity with the Annelida. It is possible that it 

 may prove a larva of some known form in this Class. 

 The specimens that I have found, however, presented 

 no differences in size or development. 



My description and figure are both less complete 

 in details than I could have wished to render them, 

 owing to the agility and to the evanescence of the 

 animal. I hoped to supply the deficiencies by the 

 study of other specimens, but this hope was disap- 

 pointed. The structure and form of the leaf-like 

 appendages of the lateral lobes, in particular, need 

 further revision. 



Fig. 1 represents it of the natural size, fig. 2, mag- 

 nified. 



