A. D. MICHAEL ON TWO SPECIES OF ACARINA. 113 



bles the mature form, except that the chitinous shield, instead of 

 covering the whole notogaster, only covers about the anterior half of 

 it, and ends with a rounded outline ; the posterior part of the 

 abdomen is membranous only, and somewhat arched in the centre, 

 sinking abruptly into a depressed channel some distance within the 

 margin, while the actual margin is raised and slightly reflexed. The 

 chitinous shield carries the two dark red patches above-named. 



The differences from all recognised families, the disproportionately 

 large and exceptionally formed mandibles, the differences of the 

 claws on the respective tarsi, the elaborate reticulation of the dorsal 

 surface, and the two pairs of beautiful branched hairs, besides 

 numerous other matters, must always make this an interesting 

 species. 



Pygmephorus spinosus, (Kramer.) 

 Plate VII. 



This species, which is the second that I shall introduce to your 

 notice, was also discovered by Dr. Kramer. It is a parasitic or 

 semi-parasitic species. Kramer found a single specimen upon the 

 mole, and figured and described it in the " Arcliiv fiir Natur- 

 geschichte," 1876, p. 254, He only found a single specimen, and I 

 am not aware that any one has found it, or at all events recorded its 

 capture, since. If this has not the beauty of the last described 

 species it is probably quite as curious ; Kramer evidently thou^fht it 

 most extraordinary, and he was right. His specimen was a male ; 

 of course he did not know that the female and immature forms were 

 different, nor probably did he suspect that it is not universally parasitic 

 in the immature stages, which seems to me to be the fact, and, 

 moreover, when parasitic in an immature stage, I doubt its being 

 confined to the mole, as I have found on flies an acarus which I can- 

 not distinguish from it. 



The most conspicuous peculiarity is the front leg of the male, 

 which is shorter than the other legs, and instead of having a 

 pointed tarsus carrying a double claw and sucker as they do, ends in 

 an almost globular mass, formed of the tarsus and fourth joint, 

 which is very large in comparison to the size of the creature. This 

 tarsus carries a single deeply curved claw, proportionate in size to 

 the tarsus itself, and closing over a fixed chitonous projection on 

 the tarsus, so as to form a holding instrument of no ordinary power. 



