ACAEI OP THE GENUS GLTCIPHAGUS. 271 



which was post-anal, and far distant from the organ called the 

 vulva, which was used only for the deposition of ova. I believe 

 that the correctness of this view is now generally admitted, not only 

 with regard to the genus Glyciphagus, but, as far as the position 

 of the bursa and organs of oviposition respectively are concerned, 

 in the Tyroglyphidse generally. If this view were not admitted the 

 present species would give an excellent opportunity of establish- 

 ing it, as will be seen by the remarks which will be found below 

 on the species which I propose to call Q-. dispar. 



At the end of this paper I have given the usual detailed de- 

 scription of each species, but I will here call attention to what 

 seems to me to be the more interesting features connected with 

 them. 



What strikes the observer first is naturally the singular 

 general appearance of the creatures, produced by the great size 

 of the abdomen as compared with the cephalothorax, by the broad, 

 flat form and almost horseshoe-shaped outline of the latter, and 

 specially by the lateral margins (and in some instances the other 

 margins) being raised and cut up into large, irregular, rough, bifid 

 or trifid lobes ; most of these lobes bearing a single eztremely large 

 spine or spike, either curved or straight, of clear, hard chitin, 

 which give the animal a very strange, and, when freshly emerged 

 and the skin is like frosted silver, a very beautiful appearance. 

 A little observation, however, discloses somethiug more worthy of 

 attention by the biologist than the bizarre appearance, which is 

 this. In the genus Glyciphagus it is usual to find a well-marked 

 distinction between the sexes, the male being usually conside- 

 rably smaller than the female, often not above two thirds of the 

 length, and rather less than the proportional breadth ; the hairs 

 are less plumose or palmate, and the posterior projection is of 

 course absent. These differences, although very apparent, are 

 after all comparatively slight modifications, not greater than 

 exist between the sexes in other genera of the same family, and 

 not such as to cause the least surprise at the creatures belonging 

 to the same species. In the larger of the two Acari now being 

 described, and which I propose to call Cr. platygaster, the ordi- 

 nary rule of the genus in this respect is well carried out. The 

 sexes show considerable diiferences, but are alike in general cha- 

 racter, and would be taken at once for the male and female of 

 the same species. The male is the smaller, in about the customary 

 proportion, and has the lobes and spikes round the hind margin 



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