ANTARCTIC ROTIFER A 47 



function. It can hardly be so with P. alata, as the processes are, from their form, 

 more vulnerable than the trunk wall would be. 



The boss on the preanal segment is of another nature. It is a thickening, and 

 may have a protective function. 



The vibratile tags are short and somewhat broadly spindle-shaped (Fig. 4e). 



Habitat. Among weeds from the Narrows between the two portions of Blue 

 Lake, pretty numerous, March 27, 1908. Afterwards found in several lakes at Cape 

 Royds and Cape Barne, always scarce and uncertain. A few could usually be got 

 when wanted from the Narrows of Blue Lake. 



It was living, among scraps of weed, at a depth of 1 1 feet in Blue Lake. 



Habits. A quiet animal and slow in its movements. When feeding, which it 

 rarely did, it could be easily studied. Under the influence of a narcotic (Eucaine) 

 it behaved in a very unsatisfactory manner. It kept the corona expanded and 

 continued feeding, but contorted itself till it was not recognisable except by the 

 side processes. No good photographs of it could be obtained, but under pressure 

 some were made which showed the internal structure and the characteristic processes. 



Affinities. P. alata, like the other two Antarctic members of the genus, belongs 

 to the central group of species. The lateral processes, which are unique in the 

 order, serve to distinguish it from all other Philodince and Bdelloids. The boss on 

 the preanal is an uncommon character. Without these processes it would be very 

 difficult to characterise. 



Philodina, sp. (Plate X., Fig. 6) 



Description. Size moderate. Corona narrow, about equalling the prominent 

 collar, and less than the trunk. Upper lip with two rounded lobes meeting in the 

 middle line. Two pale or colourless eyes. Teeth 2/2. Foot short (number of 

 joints ?) ; spurs broad short cones slightly diverging and with no interspace. 



This species, which is undoubtedly distinct from all the other Antarctic species, 

 was only once seen, and is insufficiently studied. The form of the upper lip and 

 spurs are like those of P. plena (4). There is little to separate it from that species 

 except the possession of eyes. It is doubtful if the presence or absence of eyes 

 constitute characters of even specific value, as several species are variable in this 

 respect (P. rugosa, P. macrostyla, &c.). 



It had not the red stomach of nearly all the Antarctic Bdelloids, but that might 

 merely indicate youth. 



Habitat. Among weed from the Narrows of Blue Lake. 



Genus Callidina 



Note. The genus Callidina contains a host of species, many of them not at all 

 closely related, and offering material for many genera. C. constricta and C. angularis 



