288 ME. A. D. MICHAEL ON THE VARIATIONS IN THE 



insects upon which they fed, or else were commensalists*. The nest of the mole was 

 most serviceable, because it contained several suitable species in large numbers, and I 

 could almost rely on finding them in any good fresh nest; and because I was able to 

 make arrangements to have fresh moles'-nests sent me at regular intervals all through 

 the winter, and, indeed, whenever I was in London. From this source I obtained the 

 followingspecieSjViz. : — 1. Gamasus terribUis,a large, well-marked, and interesting species, 

 which I first discovered in moles'-nests some few years since f, and which is specially 

 favourable for dissection and section-cutting. 2. ILcemo gamasus hirsutus, Berlese, at 

 least I believe my creature to be that species, which was found upon the mole, and with 

 which mine agrees thoroughly in size, general appearance, and in almost all other 

 respects ; but as the mandible of the male and the epistome vary a little from Berlese's 

 figure, I have given drawings of those organs in my creature (PI. XXXII. figs. 9, 10, 11), so 

 that if by any possibility there should be two almost similar species, mine may be known; 

 however, the mandible as figured by me differs from Berlese's figure principally in 

 possessing some additional parts, which are very hyaline and might possibly be over- 

 looked ; the epistome is a very variable organ. 3. Another species bearing considerable 

 resemblance to Hcemogamasus hirsutus, but haying well-marked differences both in 

 general appearance and in its organs, the mandible of the male being entirely different ; 

 this species is unrecorded ; I propose calling it Hcemogamasus horridus, and have described 

 it below ; it is also drawn (PL XXXII. figs. 1 to 5 inclusive). I have taken this as the best 

 type of the most important variations in the female genital organs described below. 

 4. I have also found and investigated two other species coining from the same nests, both 

 somewhat allied, and both unrecorded ; these I propose calling Lcelaps oribatoides and 

 Hcemogamasus nidi ; the descriptions will be found below r , and are illustrated, as far 

 as necessary, by figs. 6, 7, 12, 13, 11, 15. Another class of nests which provided me 

 with numerous specimens for examination were those of ants ; the researches on the 

 myrmecophilous species took place in Tyrol : the species were Lcelaps cuneifer, Mich., 

 Lcelaps Icevis, Mich., Lcelaps vacua, Mich., and Lcelaps acuta, Mich. 



Some other species will be found noticed in this paper for special variations or points 

 of interest ; but those named above have been the principal species which I have used 

 in tracing out types of organization which seem to me to be common, although to a 

 varying extent, to larger or smaller groups of Gamasina?. 



Before leaving the subject of species I think it would be well to say a few words on 

 the principal points by which species are distinguished in this subfamily, in order that 

 the sufficiency of the details of species which I have given may be understood. 



Beyond the general appearance, size, style of motion, and the general distribution of 

 the hairs or spines, these characters are — 1. The relative length of the legs with regard 

 to the body, the thickness and shape of the respective legs, and their armature ; the two 

 latter points especially in the male. 2. The form of the mandibles of the male where 



* "On the Association of Gamasids with Ants," Proc. Zool. Soc. 1891, pp. 638-653. 



t " Observations upon a Species of Gamasus supposed to be unrecorded," Journ. Quokctt Microsc. Club, ser. ii. 

 vol. ii. (1886) pp. 260-268. 



