J. MURRAY ON WATER-BEARS, OR TARDIGRADA. 57 



kinds. After some general hints as to where and how to 

 collect, and how to examine them when found, there follows 

 what I hope is a sufficiently full account of the form and 

 structure of all the genera, with the names of all the external 

 features, and of such of the internal organs as are of service in 

 distinguishing species. 



In attempting to recognise microscopic animals described by 

 our predecessors, our greatest difficulty arises from species which 

 are insufficiently described. In the case of the pioneer workers 

 this is excusable, as instruments were very imperfect, and they 

 had no idea that species were numerous ; but in modern times 

 there is no excuse for some of the very inadequate descriptions 

 which have been given. 



It is hoped that these notes will help students by pointing 

 out the characters which must be looked for. 



In Macrobiotics the claws, pharynx, and teeth must first be 

 studied, then the texture of the skin, any processes, and other 

 peculiarities. Size, colour, and movements should be noted, and 

 whether there are eye-spots. 



In Echiniscus the number and arrangement of the plates is 

 most important"; then the texture and processes, the fringe, the 

 barbs, the palps on first and last legs, etc. 



The eggs should be studied whenever possible. To prove the 

 species to which an egg belongs we have to wait for a favourable 

 opportunity ; but the hatching of eggs, or even the study of 

 well-grown young in the egg, advances knowledge so much that 

 no opportunity for doing this should be neglected. 



As a further assistance all the recognised genera are figured. 



Where to find Water-bears. 



If one is in the habit of working with what the early 

 microscopists called " infusions " of moss, more especially of 

 moss from trees, it is not likely to be long before certain little 

 animals are seen, which have a striking resemblance to bears, 

 especially when seen from the side. The resemblance is greatest 

 in the feet, with their strongly curved claws, all but the last 

 directed forward ; but many kinds have also a sufficiently bear- 

 like head. Along with them may often be seen spherical 

 bodies, covered with small spines or other processes. The bears 



