ENCYSTMBNT OF TARDIGRADA. 839 



details, — there is no "comma" in the pharynx, — the proximal end of the tooth has a 

 very large " furca," the largest known in a tardigrade. 



The claws are of a very distinct type, which is supposed to be that of M. macronyx. 

 Each pair consists of two very unequal claws, united at the base, the longer claw 

 strongly curved, and bearing at the back a strong bristle or supplementary point, which 

 diverges from the main claw about a third of its length from the point, but can be 

 traced down the back of the claw to its base. The lesser claws of the fourth legs are 

 relatively much larger. 



The eggs are spherical and are covered with little sharp conical processes, which do 

 not touch at their bases. They are rare. 



The species is common in Scotland, and has been found in England (York), Spits- 

 bergen, and Franz Josef Land. 



Professor Richters identified it at first as M. macronyx, but after the discovery of 

 the egg he regarded it as a distinct species. 



The two posterior dorsal processes, shown in fig. 1, vary greatly in size, and may 

 be absent. 



M. dispar had been known to me for a year or two before the cysts came to my 

 notice. It had been found at the margin of Loch Tay, and in various ponds near 

 Edinburgh and Glasgow. 



The spiny egg had been seen on several occasions. 



In the late autumn of the year 1906 1 washed some moss from a shallow pond 

 occupying an old quarry at Nerston, near East Kilbride, a few miles south of Glasgow. 



M. dispar, not then named, was in very great abundance. No small examples were 

 seen — all were large, and to all appearance full-grown, though there was no proof of 

 full maturity, i.e., no eggs were seen in the body. In one empty skin there was a spiny 

 egg. I had hit upon the fortunate moment for observing them, as the great majority 

 were in the act of casting their skins, and nearly all were at the same stage of the pro- 

 cess — a very few had completed it or had not commenced. Even while I watched, 

 many completed the moult, some leaving the old skin in the usual way, but most 

 remaining in it. 



The newly formed skin differed from the old skin ; it was darker yellow, and dotted 

 all over. The dots were probably pores from which a secretion exuded, as the surface 

 appeared to be viscous, and extraneous matter adhered to it. The animal moved feebly 

 and became gradually smaller ; the amount of the secretion increased, and the adherent 

 matter loaded the back with an umber-brown mass. 



Still contracting and drawing in its legs, at the same time moving more and more 

 feebly, it eventually became little more than half the original length, and assumed the 

 appearance shown in fig. 2, which represents the cyst lying in the original skin. 



At this stage it is quite rigid and dark-coloured, brown, purplish, or black. There 

 is no appearance of extraneous matter, and the surface is even, but closely dotted. It 

 is obscurely segmented, or divided by constrictions into four parts, which appear to 



