658 MR JAMES MURRAY ON 



described in the Zoologist (11), the process is very complex, and an outer and an 

 inner case are formed (see figs. 11/, 11 g). Cysts of various species are now known. 

 M. echinogenitus, M. oberhauseri, and a species of Diphascon have been found with 

 cysts like the inner elliptical cyst of M. dispar. In those cases the peculiar outer case 

 is not formed. 



Professor Richters, in a recent letter, suggests that Macrobiotus cysts were known 

 to Spallanzani. His figures are copied by Schultze (20). 



Classification. — So numerous are the species of Macrobiotus now known and so 

 varied in structure that, as a matter of convenience, it is already necessary to attempt 

 to subdivide the genus into natural groups, eventually into distinct genera. 



Any of the distinct types of pharynx, claws, or egg described in a previous paragraph 

 might serve as a basis for subdivision. It is at present quite uncertain whether any of 

 these types are characteristic of natural groups. A given type of one organ does not 

 appear to be ever invariably associated with a certain type of another organ, although 

 there are long series where two organs correspond in type. There are always some 

 exceptions, and indeed most species could be recognisably defined merely by the 

 combinations of the types of pharynx, claws, and egg. 



We may then inquire whether it is possible to found a natural classification on the 

 various types of one organ. There seems no reason for supposing that the various 

 forms of claws distinguish more natural groups than the various forms of pharynx. The 

 difference between the smooth and spiny eggs seems to point to a more profound 

 separation of the groups producing them, since there is not only the widely different 

 eggs, but their future is provided for in a totally different manner, — the spiny eggs 

 being deposited and left to their fate, while the smooth eggs are enclosed in a sack 

 formed of the cast skin of the parent. 



M. oberhauseri, Doy. ? (2). (Plate IV. figs. 27a to 27 d.) 



Though recorded in the Tardigrada of the Scottish Lochs (6), that record cannot be 

 trusted, as I did not then sufficiently understand the species. Having been favoured by 

 Professor Richters with living examples and slides of the animal, a brief diagnosis can 

 now be given. Claws of the type common in the genus Diphascon, one pair nearly equal 

 and joined at the base, the other having one very long slender claw, movably attached 

 to the middle of the back of the shorter claw. Pharynx with 3 nuts in each row — a 

 small one attached to the gullet, and 2 larger free nuts. 



The brown pigment is a very warm colour, inclining to madder ; it is variable, and 

 may be absent. 



Animals with claws and pharynx as described above are frequent ; one pigmented 

 example in moss from the pier, Fort- Augustus. 



An animal having the claws and pharynx of M. oberhauseri was seen to hatch out 

 of an egg found in Loch Ness, December 1906. 



This egg was of the hastatus type. The egg is round, the hyaline layer thinner 



