DESCRIPTIONS OP GENERA AND SPECIES. 291 



parallel ridges, which start from the edge next the 

 median line of the body, and run about half across the 

 plates. On the ventral surface of the body covered by 

 each holding-plate is a strong, irregular, compressed, 

 chitinous ring with a hollow centre; the outer or 

 lateral edge of this ring is much thickened, and there 

 is a spur on the anterior portion of the ring just where 

 the thickened part begins. Haller considered that 

 each homopial plate was mounted on this ring. I 

 think that this is a mistake ; it seems to me that the 

 hair to be held lies in the hollow of the ring and passes 

 over the ring itself, and that the homopial plate folds 

 over it and holds it firmly against the ring. Just 

 inside the chitinous ring is a strange spoon-shaped, 

 moveably articulated hair or process. Haller was 

 uncertain what their function might be, but suggested 

 that the contents of the expulsory vesicles, which are 

 a red liquid, might be discharged into them. This 

 scarcely appears probable ; the contents of these 

 vesicles are of an oily nature in all Tyroglyphidas 

 where they are known ; and this would not facilitate 

 holding the hair. I have not been able, however, to 

 observe what are really the functions of these spoon- 

 like processes with any certainty. 



Habitat. This species, as far as I know, has only 

 been found in squirrels' nests and on the squirrel ; it 

 has been recorded in England, Germany, Italy, and 

 the Netherlands. 



PRINTED BY ADLABD AND SON, 



BARTHOLOMEW CLOSE, E.G. ; 2O, HANOVER SQUARE, W. 

 AND ^DORKING, 



