78 THE EOTIFERA. 



Ehrenboi'f!; formed the genus Cephalosiplion of his family of the Flosailaiicea to receive 

 a single species, C. Limnias, one specimen of which he found ou Ceratophyllum at Berlin. 

 His characters of the genus are as follows: '' Cephalosiplion, "E,. Rotatory organ bi- 

 lobed, eyes two, sheath or lorica single, two little frontal horns enclosing the siphon; " 

 and those of the species are : " C. Limnias, E. Sheath membranaceous, ringed." 



The characters of the genus and species were given in Pritchard's "Infusoria" 

 (edition 1801), but no one after Ehrenberg seems to have actually seen the animal itself, 

 till Mr. Slack found it in a pond in the neighbourhood of London in 1800 on Aiiacharis 

 alsinastrvvi. Mr. Slack supposed it to be the young of Limnias ceratophylli, and gave 

 a brief description of it under that name in 1801 in his " Marvels of Pond Life " {loc. cit. ). 

 He noticed the creature's bi-lobed corona, as well as the great length, flexibility, and 

 peculiar action of the dorsal antenna " thrust on this side, and on that, as if to collect 

 information for its proprietor." Mr. Gosse in the same year, in a paper entitled " A 

 Rotifer new to Britain (Ccplialosiphon Limnias)," gave a full description with a plate 

 of three figiu-os of the new Eotiferon, taken from some specimens sent to him by Mr. 

 Slack. These specimens seem to have been injured by the journey, as they did not 

 expand freely, and so led Mr. Gosse to draw the corona with a butterfly-shape, which 

 healthy specimens do not possess. Mr. Gosse, however, fully worked out the Rotiferon's 

 structure, with the exception of the secreting and vascular systems ; and he described 

 and figured the " frontal horns " or hooks, which are situated like the hooks of Melicerta 

 ringens, one on each side of the dorsal antenna. This Eotiferon is very partially dis- 

 tributed. It w'as upwards of twenty years after I first began to search for Rotifera in 

 the neighbourhood of Clifton, that I first lighted on it ; and Miss Saunders has had a 

 similar experience at Cheltenham. In 1875 I found a group of them on a leaf of a 

 Potamogeton in a pond at Nailsea, near Bristol, and I made a careful drawing of the 

 group (PI. VI. fig. 3). The tube is horn-shaped tapering to the foot ; generally neater 

 and more compact than that of CEcistes crtjstallinus, but coated with much the same 

 sort of yellow-brown material. 



The trunk is small compared with the foot, which is long and slender. The animal 

 arches its dorsal side (fig. 3), in a manner common among free-swimmmg Rotifera, but 

 unique among the fixed ones, which, in all other instances, arch tlie ventral side, so as 

 to bring the entrance to the buccal funnel uppermost. C. Limnias has that entrance 

 almost hidden by the bending over of the corona. The arrangement of the double ciliary 

 wreath is precisely that of the other Mdiccrtadce. The usual pair of clear vesicles 

 ( salivary glands ? l rest on each side of the top surface of the mastax, wliich is high in 

 the neck towards the dorsal side ; and the ciliated buccal funnel slopes across to pass 

 between them. There are a narrow oesophagus, two globular gastric glands, cylindrical 

 stomach, short intestine w-ith uptui-nod rectum, ending in a cloaca rather low on tlio 

 dorsal surface. 



Of the vascular system nothing has been seen ; but Mr. Gosse Hoc. cit. " Intcll. Obser.") 

 describes the nervous ganglion as " a grey cloudy mass of irregularly-lobed form, imme- 

 diately below the antemia, and behind the discal mammilla." I thought once or twice 

 I caught sight of a ventral sctigerous pimple just below the entrance to the buccal fm^- 

 nel, but I am not sure about it : there may be a pair of them there. The dorsal antenna 

 is the striking feature in C. Limnias. When the animal has closed its corona and retired 

 into its case, this slender transparent rod, with a brush of setie at the top may be seen 

 gently moving about to see if the coast is clear. When rtitisfied that it may come up 

 safely, Ccplialosiphon hitches its long antenna over the side of the tube, and hoists 

 itself up by it into a great curve ; it then straightens its body and unfurls its corona. 



The long antenna is not always straight ; it is occasionally bent into long curves like 

 the process of /■'. cornnta, but its changes of form are slow. Its base is broadened out 

 like that of a rose-thorn, as if to give it a good purchase. Two red eyes arc conspicuous 

 in the adult, a little below the dorsal surface, one on each side of the antenna, and close 

 to the nervous ganglion. 



