416 
Avgas persicus 
dorsal surface of the canal; while the other set comprises the ventral 
genital muscles, which originate from the ventral body wall and are 
inserted on the ventral surface of the ductus ejaculatorius, further 
forward than the site of insertion of the corresponding dorsal series. 
The Accessory Glands. 
Plate XXVII, figs. 1-4. 
The accessory glands comprise a large and complex mass of peculiar 
glandular tissue which almost completely surrounds and conceals the 
seminal vesicle and the terminal portion of the vasa deferentia; and, 
on account of the dense chalky-white appearance which they usually 
present, they have been frequently termed the “ white glands.” 
Glandular appendages of divers forms are generally found to be 
associated with the terminal portion of the genital tract in the Arach- 
nida, but, so far as we are aware, in no representative of the class do 
they ever attain the high degree of development which they exhibit 
in the Ixodoidea. 
Heller gave a very good accouut of their gross structure in Argas 
persicus, though some of his observations were not free from error 1 . 
Pagenstecher described the structure in Ixodes ricinus as a “seminal 
vesicle 2 ,” and expressed doubts as to the existence of any actual accessory 
glands in connection with the male genitalia of this species. His figure 
(Taf. II, fig. 12) of the male genital organs, however, leaves no doubt 
whatever as to the presence of the accessory glands in this species. 
It may be remarked that Pagenstecher made some very strange errors 
in his observations on the anatomy of the genital organs of Ixodes 
ricinus, for, in both sexes, he failed to recognise the median, trans¬ 
versely-placed gonad, and described the dilated portion of the oviduct 
and of the vas deferens as the ovary and testis respectively. The more 
recent literature, for the most part, contains only casual references to 
the subject of the accessory genital glands of the male tick ; the only 
author, so far as we know, who has attempted a detailed description, 
being Bonnet, whose observations, so far as they go, coincide with ours 3 . 
In its external appearance, the accessory gland is a large bilaterally- 
symmetrical organ which rests on the floor of the body cavity, its 
anterior extremity, consisting of a single pair of club-shaped lobes, 
extending almost to the postero-ventral margin of the basis capituli, 
1 Heller, C. (1858), pp. 319, 320. 
8 Bonnet, A. (1907), pp. 120-122. 
2 Pagenstecher, H, A. (1861), p. 39. 
