Internal Anatomy of Uropo'la Krameri. By A. D. Michael. 13 



of tlie genital plate (as mentioned below). Secondly, the processes 

 may hold the egg in position so as to assist in its being forced out by 

 spasmodic contractions of the vagina. Thirdly, it is not impossible 

 that Uropoda Krameri may be ovo-viviparous, the young larva 

 escaping from the egg at the moment of deposition. If this be so, 

 the forcing of the egg through the narrow opening of the vestibule, 

 between these numerous processes, would probably serve to break and 

 strip off the thin chorion of the egg, allowing the larva to escape. 

 This last explanation is rendered more probable by the very advanced 

 state of development in which the eggs are found in the oviducts, and 

 also by the fact that where I found this TJropoda so plentifully there 

 were numerous larvae and nymphs, but 1 was not able to find any 

 eggs. I tried keeping a number of the Uropoda in confinement in 

 a cell, but I did not get any eggs. The creatures, however, are 

 difficult to keep in good condition in confinement, which may possibly 

 explain the absence of eggs from my cell. 



The genital plate (fig. 16 ; and figs 1, 18, gjp) is the external door 

 in the ventral surface by which the egg, or larva, if the creature be 

 ovo-viviparous, emerges from the body of the mother. It is a 

 triangular plate with curved sides, and is slightly convex externally 

 and concave internally. Its lateral margin is thickened and slightly 

 turned in. The posterior edge is almost straight, with very slightly 

 rounded corners. At this hinder edge the plate is attached on the 

 interior to the ventral plate by the quasi-membranous lining common 

 to both ; thus a ginglymus hinge is formed. The genital plate 

 exactly fits into the opening in the ventral plate, but the anterior end 

 of the genital plate is prolonged so as to form a long chitinous 

 point ; this has not any opening or depression in the ventral plate to 

 receive it, but lies wholly outside the latter. The lateral edge of this 

 genital plate has a thin, chitinous, curved, more or less triangular 

 lamina standing on edge slightly within the lateral margin of the 

 inner side of the plate (fig. 16) ; the broad part of this lamina is the 

 hinder part, and to its upper angle the occlusor muscles of the plate 

 are attached by tendons which unite to form one long and very 

 substantial tendon, which is inserted at the above-named point of 

 attachment, in the manner so frequently found in the Acarina 

 especially the Orihafidse. The size of the genital plate is really 

 surprising ; it occupies almost the whole space between the legs ; its 

 posterior edge is considerably behind the coxae of the fourth pair of 

 legs, while its anterior point reaches those of the first pair of legs, 

 and almost touches the singular tactile organ found in most Gamasids, 

 and which Kramer has called the ventral palpus (" Bauch-Taster "), 

 and Winkler considers to be the labium. Of course this plate greatly 

 more than covers the opening of the vestibule, indeed that openino- 

 only corresponds to about the anterior half of the genital plate. This 

 anterior portion of the genital plate is strengthened by a thin interior 

 plate about the size and shape of the opening of the vestibule ; and 

 all this plate, except a small part at the hind margin, is thickly set 



