284 ME. A. D. MICHAEL ON THE VAEIATIONS IN THE 



Claus, not knowing of Dr. Kramer's paper, independently discovered the existence of 

 the heart in Ganiasidse, and published the result of these investigations in a short but 

 excellent paper *, in which the heart and its accessory organs were described far more 

 exactly than Kramer had done, and which was illustrated by a very good plate, where 

 the surrounding organs, &c, were also shown. 



It was possibly his studies for this purpose that drew Winkler's attention to the group ; 

 at any rate, in 1888 the first paper was followed by a much more important treatise f. 

 This admirable and beautifully illustrated paper is incomparably superior to anything 

 else which we have upon the internal anatomy of the Gamasiuse ; indeed, it may practi- 

 cally be said to comprise all that is, up to the present, recorded on the subject, and it is 

 most clearly explained and carefully figured. The principal types which he takes are 

 what he calls Gamasus crassipes, Linn., and Vropoda scutata, Koch (?) ; he, however, 

 less fully refers to and figures G. fucorum, De Geer, a nymph of Poecilochirw carabi, 

 Canestrini, and Hyoaspis nemorensis, Koch. He also states that he has examined speci- 

 mens of the genera Holotaspis, Kol., Sejus, Koch, and Epicrius, Can. Still I think the 

 principal stress of the paper must be considered to be laid upon the species called 

 Gamasus crassipes. As to this, I have been enabled to follow him, and have frequently 

 dissected this creature, and as a result I wish to express my admiration for the excellence 

 and accuracy of Winkler's work and the beauty of his drawings. I have not myself 

 dissected the other species which he names except Gamasus fucorum, and in three genera 

 he does not name the species, so that I cannot say anything about the matter ; but I 

 have not any reason to doubt his being as correct with regard to them as with regard to 

 his Gamasus crassipes. 



It will be observed that I say above, " what he calls Gamasus crassipes." I use this 

 expression because it seems to me that the species is not the Gamasus crassipes of 

 LinnEeus. This is really quite immaterial, and Winkler does not claim to be a specialist 

 in the identification of species of Gamasidse. I only mention it to avoid confusion in 

 case anybody should at some future time dissect the true species and not find it quite 

 agree with Winkler's description. 



When I say that it is not the Gamasus crassipes of Linnseus, it must be explained 

 that Linnseus's own description would not enable anyone to identify the species or even 

 the family ; it would be equally applicable to a very large number of creatures widely 

 different from each other. Schrank's description in 1781, might enable the student to 

 identify the family, but nothing more. In 1804 Hermann published a description with 

 figures X, which are good. This must really be looked on as the first definition of the 

 species ; it certainly is not the Gamasus crassipes of Winkler. 



With regard to the Uropodinse, I cannot say that I can confirm Winkler's views quite 

 as exactly as I do respecting G. crassipes ; the larger part of what he says is undoubtedly 

 correct of the species to which he refers, and which again I think is not the Vropoda 



* " Das Hcrz der Acariden," Arbeit, d. Zool. Inst, zu Wien, T. vii. (1886) Heft 1, pp. 111-118. 

 t " Anatomie der Gamasiden, - ' ibid. T. vii. Heft 3, pp. 317-354. 

 t ' Memoire apterologique,' Strasbourg, 1804. 



