220 



HARDWICKE'S SCIENCE-GOSSIP. 



an epizoic parasite upon Daphnia pttlex and other 

 aquatic animals. In a gathering from a pond near 

 Woodford, in Epping Forest, nearly every individual 

 of this cladoceran was attended by one, or several, of 

 these rotifers, the latter evidently in more or less 

 permanent quarters, with their deposited ova beside 

 them, upon the Daphnia's shell. The cause of the 

 Proales' presence was not difficult to determine in 

 this case, for the water-fleas were all more or less 

 thickly infested with clusters of small epistylids, 

 upon which some of the rotifers were observed 

 to feed, leisurely moving along and nibbling with 

 their trophi at the infusorians one after another, each 

 of the latter wholly disappearing in a few seconds. 

 Not only upon Daphnia pulex did specimens of this 

 rotifer occur ; upon search being made several larva? 

 of the May-fly, and also a single Cyclops serrulatus, 

 were found to be likewise encumbered with them, 

 colonies of infusoria being present in each case ; 

 curiously enough, not a single individual of Simo- 

 cephalus vetulus examined (and there were not a few 

 in the water) bore either rotifers or infusorians. The 

 rotifers' eggs were attached to the host's carapace by 

 a drawn-out thread of hardened mucus. Upon one 

 Daphnia, a Proales had taken up its quarters right in 

 the very midst of a thick cluster of Epistylis ; seeing 

 also that three of its ova lay beside it, developing, the 

 fate of the unconscious infusorians in the near future 

 appeared by no means uncertain. In such manner 

 did this rotifer, for the nonce, enter into commensal 

 partnership with the water-fleas and insect larvae, 

 gradually freeing them from their swarms of adherents 

 in return for its transit and food ; as, however, the 

 Daphnias could have very easily cleared themselves 

 of the annoying hosts at their next moult, it follows 

 that the Proales' services scarcely compensated for 

 the extra fatigue in carrying these bulky rotifers 

 about. 



In concluding this paper, as a further illustration 

 of the quasi-parasitic habit of Proales, I have to 

 bring forward a species which seems to fall within 

 the limits of this genus, and which is certainly an 

 undescribed form. I propose to give this the name 

 of 



Proales daphnicola. 



In the latter part of October of last year, on two 

 occasions, a pond at Leytonstone, Essex, was found 

 to be swarming with numbers of fine red Daphnia 

 pulex ; upon many of these occurred, roaming about 

 over the carapace, examples of an illoricate rotiferon 

 which at once struck me as unfamiliar. Eggs were 

 also present attached to the cladoceran's shell, just 

 as in the similar case of P. petromyzon already 

 noticed ; and, as with that species, the rotifer could 

 leave the Daphnia at will, and swim freely. A few 

 notes and a rough sketch of the creature were taken, 

 and its internal anatomy found to present nothing 

 worthy of special remark, the particulars secured 



being detailed below. I have not since seen further 

 examples of this form either in subsequent dips from 

 the same pond or elsewhere ; the swarms of 

 Daphnias rapidly decreased with the advent of cold 

 weather, and very soon not a specimen was to be 

 taken from the pond. I am constrained therefore to 

 give an account of this creature now, notwithstand- 

 ing the paucity of particulars, in the hope that others, 

 or I myself, may come across specimens in the 

 ensuing autumn, and fill up any blanks in the present 

 description. 



The form is fairly plump, thinning behind without 

 abrupt distinction between the body and foot. The 

 coronal face is obliquely truncate, abundantly 

 ciliated. I saw no frontal proboscis. The mastax of 



Fig. 125. — Parasitic Rotifer (Proales daphnicola, n. sp.), 

 slightly compressed. 



moderate size, the contained trophi of the usual 

 notommatous type. Gastric glands rather large, 

 angular. Ovary small. Brain a clear transparent 

 sac of but moderate length, no trace of an eye being 

 visible. Dorsal antenna not discerned, but the 

 lateral antennae were distinct when the animal was 

 under compression, placed about half way down the 

 body upon the dorso-lateral surfaces, and each con- 

 nected with a nerve-thread running up towards the 

 front of the body. Lateral canals and their tags were 

 present, also a moderate contractile bladder below the 

 intestine. The muscular system, so far as observed, is 



