Mr. H. J. Carter on Microscopic Filarictoe. 99 



them have become known ; and therefore the generic name of 

 " Urolabes*," which I have employed, should only be viewed as 

 provisional. It has been chosen from the striking habit which 

 all these worms have of attaching themselves to some object by 

 the tail, whether it be by embracing it or by adhering to its 

 surface. Hence the tail would appear to be both prehensile and 

 adhesive, if not suctorial. Having once fixed themselves in this 

 way, they keep up an undulating movement from the tail for- 

 wards, which, in the absence of any evident purpose, seems 

 more for respiration than anything else. They can also, when 

 once attached to any soft substance, hold on until they wriggle 

 themselves into its interior, either for concealment or in search 

 of food ; and this peculiarity is not more striking in the micro- 

 scopic Filaridre than it is in the young Filaria Medinensis. 



Their especial habitat is more in the midst of the gelatinous 

 Algae, Oscillatoria, Gloeocapsa, &c., than in any other place, 

 where they not only meet with gelatine, starch, and oil for food, 

 but frequently with a nitrogenous product in the shape of pro- 

 toplasm, which is liberated from the decomposition of the vege- 

 table cells with which such Alga? are generally associated ; and 

 they abound in such matter not only in the fresh- and salt- 

 water accumulations about the island of Bombay, but every- 

 where during the " rains;" so that probably there are many 

 which only come into life and breed, like some of the Na'idina, 

 during this part of the year. 



The males and females may be generally found together 

 where the species is plentiful; but this is frequently not the 

 case, which, together with their microscopic size and constant 

 motion under examination, or while they retain the least life, 

 renders them very difficult to study, and requires an amount 

 of time which very few have at their disposal to bestow upon 

 them. Hence I have thought it better not to withhold the de- 

 scriptions of those which follow Urolabes palustris because they 

 are not equally detailed, but to offer them for publication so far 

 as they go, that they may be completed by others, and thus the 

 time that has already been spent upon them not altogether lost. 



A knowledge of the external parts and the whole of the ali- 

 mentary canal is easily obtained ; and the anus and vulva have 

 been assumed to be ventral in all, from analogy, as there is no 

 other means, from their roundness and minuteness, of deter- 

 mining this in any other way : but many individuals are required 

 before the fonn of the generative organs can be figured cor- 

 rectly, as these have to be pressed out before they can be seen ; 

 and, under such rough treatment, it is only one here and there 



* From ovpu, cauda, and Xa/Sw, prehendo. " 



7* 



