290 MR. A. D. .AJICIIAEL ON THE VAEIATIONS IX THE 



There is not any intromittent organ known in the Gamasinse ; tlie ductus ejaculatorius 

 communicates directly with the exterior by a roundish opening (PL XXXIII. figs. 29, 

 31, 33, i/«), which, in most genera, is placed in the median line immediately in front of 

 the sternal plate, and thus in the soft cuticle which is found between that plate and the 

 hypostome, i. e. the ventral side of the oral tube (or rostrum). Immediately in front of 

 tlie genital opening is a curious narrow flap of chitin truncated aud terminated by 

 two slightly feath(!red setse (figs. 2 & 36, bp) ; it is hinged l)y its proximal edge to 

 the cuticle, is hollow, and has a fine nerve distributed to it. It is found in lioth sexes, 

 although tlie female genital aperture is distant from it. Kramer calls this organ the 

 breast-palpus ; AVinkler considers it to be the homologue of a labium ; I feel doubtful 

 about this homology, and therefore speak of it in this paper by the neutral name of 

 " the bipilate appendage." It is usually found in the GamasinsB, and does not cover 

 the genital aperture. 



The genital organs of the male of Gamasus terrihilis are delineated by fig. 29 ; a 

 glance at that drawing will show how widely they differ from those of Winkler's species : 

 that diU'ercnce is not in any degree a question of time of year or surrounding circum- 

 stances ; I have examined the organs in large numbers of specimens at all seasons, but 

 invariably with the same result. The unpaired, globular, central testis is entirely 

 absent ; in its stead wc have two very large doubly-pyriform organs, i. e. each testis is 

 more or less of the shape of two pears with their thick ends placed together ; but the 

 hinder pear stands somewhat perpendicularly, and leans and curves inward and somewhat 

 forward, while the anterior pear lies nearly horizontally, but curves inward. It must 

 not be supposed that these two pear-shaped pieces are in any way separate organs ; they 

 are thoroughly continuous; only tli(!i'o is an external, not very deep, rounded constric- 

 tion at the jjoint where the somewhat perpendicular part ceases and tin; horizontal 

 commences. Tlic liinder and upper ends of the two bilaterally symmetrical testes are 

 joined together by a very thin connection near the dorsal surface, just in the situation 

 (as regards tlie genital organs) wlun'o tlie single testis is in Winkler's species; although 

 in that species, with its long vasa defertMitia, the testis is much nearer the anal end of 

 tiic creature. It will be seen from the drawing tliat iJie long, tliin, well-marked vasa 

 deferentia of (J. crasslpes arc not to b(; iniiiid in (J. lerribllis; indeed, vasa defei'cntia can 

 scarcely b(; said to exist at all in the latter species : a minute portion of the organ on 

 each side, close to the ductus ejaculatorius, may be called a vas deferens ; but there is not 

 any r(;al demarcation between that aud the testis. Of course it migiit be said that the 

 whoh) horizontal portion of the organ, on ea(;h side, was a vas deferens; but the form of 

 tiiat part, its entire continuity with the hinder part ol' the; testis, tiie solidity of its 

 contents, and their steadily ])rogressive development from the liind(,'r to the anterior end 

 of what I call <hc testis seem against that vi(;w. 



The ductus (ijaeuhitorius and the great accessory gland are practically similar to those 

 of G. cr/tsN/pcfi, exce])t that the former is perhaps a, litllc, longer in proportion, and not 

 quite so uniform in diameter as in G. crassipea ; aud that tiu! latter is without the 

 curious narrow recurved portion at the posterior end figured by AVinkler. 



Doubtless, in spite of the extreme dissimilarity between the above described ori-'aus in 



