ANTARCTIC ROTIFER A 53 



freezing and thawing. It was the only species subjected to the heating experiment, 

 in which a proportion of them lived after the bottle containing them (in the dry con- 

 dition) was immersed in boiling water for a short time. It was one of the rotifers 

 which was to be seen alive and active in London in September 1909, after being dry 

 for about a year, and spending some months in tropical and subtropical climates. It 

 revived in about an hour after being moistened. It was immersed in sea-water, and 

 in the much more saline fluid obtained from under ihe ice of Green Lake (of which it 

 is a native), and kept there for one month, after which it revived quickly when trans- 

 ferred to fresh water. The diameter of the contracted animal in fresh water was 

 225 p. in the brine of Green Lake it contracted to 150 p, or two -thirds of the normal 

 diameter. 



It is indifferent to the interruption of its active vital functions by freezing, often 

 for long periods, and quickly resumes activity when thawed. The development of the 

 young likewise does not appear to suffer from its interruption at any stage. In con- 

 sequence of interruption development may often take many years for its completion, 

 but in the periods when the lakes are melted it probably only occupies a few days, 

 and many generations may be completed in the few weeks of summer. 



Affinities. A. grandis shows most resemblance to A. vaga Davis (12). The 

 pectinate margin to the mouth is a character which may readily be overlooked in 

 species of this genus, as the structures of the head of an Adineta are very difficult to 

 see, on account of the restless contortions of the animal. The pectinate border is 

 easily seen in A. grandis owing to its large size. 



The species may be a derivative of A. vaga, but of very long standing, as the 

 profound changes show. A different mode of reproduction has been adopted, and 

 the form of spurs and rostrum, &c., changed. The ciliated surface of the face of 

 A. vaga is described as divided into two parts by an unciliated band. This is not 

 the case with A. grandis, in which there is no perceptible interruption of the furred 

 surfaee from side to side. 



Adineta barbata, Janson? (20) (Plate XII. , Figs. 9a-9c) 



Description. Of moderate size. Head ovate ; rostral tip produced laterally into 

 little sharp points ; lamellae long, slender, curved, rounded, accompanied by several 

 long bristles ; spurs divergent, curved, tapering, acuminate. 



While corresponding in general to the type of A. barbata, the animal found at 

 Cupe Royds differs in two particulars : the spurs taper from the base and are 

 acuminate ; in the type the thickness is maintained to near the tip, and the tapering 

 is then abrupt ; the processes on the rostrum which correspond to the lamellae of 

 the Philodinadse are very long and slender, and in dorsal view look like antennae of 

 insects. 



Jansou does not describe the lamellae as of this narrow elongate form, and his 

 figure shows them quite moderate. The difference is of specific value, but as the 



