ANTARCTIC TARDIGRADA 99 



The egg is extremely variable. It is one of the "areolate" type (see M. 

 areolatus, p. 167). The shell appears to be double, and the enclosed space is 

 divided into a number of equal cells or chambers by septa which appear on the 

 surface as a hexagonal reticulation. From certain hexagons, at equal distances 

 apart, the processes spring. They are separated by one hexagon. They vary 

 greatly in form. Some are rounded at the top and appear as semicircles in optical 

 section : others are conical and acute : others again acuminate, with slender points. 

 The turgidity of the processes causes pressure upon the surrounding hexagons, and 

 thus interferes with the regularity of the reticulation. Sometimes the processes 

 appear wrinkled or shrunken at their bases, when they may become smaller than the 

 intervening polygons. . 



Habitat. Among moss collected by R. E. Priestley at the Stranded Moraines on 

 the west side of Macmurdo Sound, very abundant, eggs also numerous. 



After being dry for more than a year, several adults were found alive when the 

 moss was moistened on February 15, 1910. Some eggs were hatched, thus completing 

 the life- history of the animal. 



M. polovris has affinities with a great many species forming what may be called 

 the hufdandi group. Most of the species are characterised by eggs having very 

 distinctive characters, but it must be admitted that several of them could not be 

 recognised with certainty, unless the egg were found, and its relation to the animal 

 demonstrated by hatching or otherwise. It is not one of the species nearest to 

 M. hufelandii, which have very wide gullets. It is only necessary here to point out 

 the characters in which it differs from those species which have somewhat similar eggs. 



The nearest relative is perhaps M. ineridionalis , Richters (40), with which I at 

 first identified it. Professor Eichters' figure does not give all the details necessary 

 to separate the species, but he informs me in a letter that the processes of the egg 

 are hemispheres with a small discoid projection on top, and that the surface is not 

 reticulate in the manner described above. This form of egg I know as occurring on 

 Scottish mountains, and it is quite different from M. polaris. 



M. echinogenitus and M. areolatus have the claws joined near the base only : the 

 former has not a reticulate shell, and the latter has a much larger egg and no comma 

 in the pharynx. 



M. montanus (nee p. 116) has the processes hemispherical, almost touching at 

 their bases, and the surface not reticulate. M. harmsworthi has the processes 

 acuminate, and close together on the shell, which is not reticulate. 



Macrobiotus oberhciuseri, Doyere (2) 



As an Antarctic species this is only known from a single example, found in moss 

 from the High Moraines at Cape Royds, January 1909. A photograph of the animal 

 from life is shown in Part 2 of this volume, Plate III. Fig. 11. 



