ON THE TARDIGRADA OF THE SOUTH ORKNEYS. 327 



in only one of these species did I succeed in connecting the egg with the animal which 

 produced it. The others must remain unidentified till the living animals can be studied. 



In the other section the smooth oval eggs are deposited several together in the 

 moulted skin, and here again, though several species were seen, only one could be fully 

 studied, and that appears to be a hitherto undescribed species. 



In all the species figured it will be noticed that the pharynx is relatively extremely 

 small. The size of the pharynx has been used by authors as a specific character. Of 

 little service at any time, owing to variability, the size of the pharynx is quite value- 

 less in the case of the South Orkneys species. In these, I think, the muscular bulb is 

 greatly contracted. 



A. Spiny Eggs, laid singly, free, not in the moulted skin. 



Macrobiotus furcatus, n. sp. (Plate II. figs. 60 to 6d.) 



Specific Characters. — Large, hyaline, in form like M. hufelandi, with claws in pairs, 

 which are united half way up as in that species, but with stronger supplementary 

 points. Teeth slightly curved, with a small furca. Pharynx very small, oval or 

 rhomboid, thickenings in each row, — first, short nut next gullet, then three equal 

 rods, about twice as long as broad, then a very obscure small nut. Dark eyes. Eggs 

 spherical, with conical processes, which are dichotomously branched twice or thrice. 

 Length about 600 m, pharynx of adult 46 m long. 



By far the most abundant Tardigrada collected. The eggs were still more numerous 

 than the adults. By squeezing one fully developed young out of the egg, I was able 

 to establish the identity of structure both of cftiws and pharynx with the commonest 

 adult Macrobiotus in the collections. 



This species may be regarded as the South Orkney representative of M. hufelandi 

 (14), with which it has affinities in all points of structure. The processes on the egg are 

 most conspicuously different, yet their form is the same, only they are dichotomously 

 divided at the apex. Most of the processes are twice furcate, with slight traces of a 

 third division. Some have a perforation lower down than the first fork. The egg 

 measures 83 m without the spines, 105 m over the spines. The pharynx differs in the 

 complete separation of the first two rods, which in M. hufelandi are almost joined. 

 The pharynx is relatively much smaller, but it is probably much contracted. 



The claws are very similar to those of M. hufelandi, but the supplementary points 

 are almost as large as the main claw. I could never see clearly two distinct supple- 

 mentary points on the same claw, as Eichters found to be the case in M. hufelandi ; 

 but the appearance in optical section (fig. 6c) supports the belief that there are two 

 here also. Owing to diffraction effects the true form of supplementary points on the 

 claws of Macrobiotus is difficult to make out. 



The processes of the egg have a very remote resemblance to those of M. granulatus, 



