INTERNAL ANATOMY OF THE GAMASIN^. 283 



: ' First in order of date must be mentioned the paper by M. Meg'nin, of Versailles, in 

 which he expresses the opinion before referred to *. This contains a careful description 

 of the external anatomy and trophi of some of the species of Gamasus and TJropoda, 

 particularly the latter. The paper also deals, to some extent, Avith the internal anatomy, 

 but in a far more general and slighter manner, and this portion of the description is far 

 from being entirely correct, particularly that portion Avhich refers to the genital organs— 

 e. g., he attributes to the male the possession of a penis, which does not exist — and the 

 description of the female reproductive organs is still slighter than that of the male ; 

 while the information given as to the time and mode of coition was, as will be seen in 

 this paper, entirely incorrect ; still M. Megnin's paper was the beginning of our know- 

 ledge of the anatomy of the group, and a large part of the external anatomy especially 

 still stands as quite correct and as the best existing description. 



Almost at the same time as M. Megnin's memoir. Dr. P. Kramer, then of Schleu- 

 singen, now of Halle, published a paper on the GamasidiB f. This paper contains, inter 

 alia, considerable information as to the internal organs; chiefly, however, such as might 

 be obtained by a careful study of more or less transparent specimens without actual 

 dissections or sections. The drawings of the internal anatomy are few, and are chieily 

 confined to outlines of general form, some of which scarcely correspond with anything 

 yet known to me ; but the variety of internal organization in the Gamasidas, and, indeed, 

 in the Acarina generally, is so considerable in different species that I should be sorry to 

 say that they may not be correct. It is in this paper that the existence of a heart in the 

 Gamasidse was first made known. 



In a subsequent paper (1882) J, which is chiefly devoted to the Uropodinaj, Dr. Kramer 

 gave considerable information as to the various chitinized plates of the external skeleton 

 of the Gamasida;, but did not add to the then existins; knowledo'e of the internal 

 anatomy. 



In a still later memoir § uj)on Malarachne E.alichoeri, a remarkable parasite belonging 

 to the Gamasinse, found originally by Prof. Allman in the nares of the Seal ]|, the same 

 author carried the knowledge of the internal organization much further ; he described 

 and figured the cvirious tendinous platform in the middle of the body (episternite), which 

 is suspended from the dorsum by muscular bands, and which forms a kind of inner 

 skeleton, whence arise the powerful muscles that move the legs, &c. He also treats 

 correctly of many other matters, which, although described only for the particular 

 species, prove to be of much wider range. 



In the folloA\ing year (1886) Herr Willibald Winkler, with the assistance of Prof, 



* " Memoire sur rorganisation et la distribution /oolojiiquc ties Acariens de la famille dcs (Jamasidos," Robin's 

 .lourii. de FAnat. et de la rhysioL, May 187(i, pp. 298-366. 



t " Zur Naturgeschiclite einiger Gattungen aiis der Familie der Gamasiden," Archiv fiir Xaturg. 1870, Bd. i. 

 pp. 46-105. 



% " Ueber Gamasiden," Archiv fiir Naturg. 1882, lid. i. pp. 375-434. 



§ " Ueber Halaracluu ffalkhcen, Allm.,'' Zeitsch. fiir Naturwiss. Ed. Iviii. (1885). 



II "Description of a new Genus and Species of Tracheary Arachnidans," Ann. & Mag. Nat. Hisl. 1847, vol. xx. 

 pp. 47-52. 



42* 



