INTERNAL ANATOMY OF THE GAMASIILE. 301 



may for the moment be either wholly closed or slightly or considerably open ; when open it 

 forms the entrance to a much smaller pyrifortn sac (figs. 48, 49, cs), joined to the first by a 

 short wide neck ; or, rather, perhaps the second is to be regarded as a continuation of the 

 fii-st, but the neck between is usually slightly twisted. I propose calling this second sac 

 the "cornu sacculi," as after examining its forms in various species I consider it as in effect 

 a prolongation of the sacculus ; the histology is identical. The hroader end of the cornu 

 is toward the sacculus, but it turns almost perpendicularly downward (fig. 49 J, so that 

 its apex is the lowest part ; this again is not ahsolutely closed, only constricted, hut the 

 constriction is very close. The apex is attached to the camera spermatis, which it enters 

 low down, practically at the base or from below. The wall of the cornu spreading out 

 after the constriction, and being in fact continuous with the tunica propria of the 

 chamber, thus there is an entrance from the cornu through the camera spermatis to the 

 ovary, although it often requires long and careful examination of many specimens to 

 make sure of the fact ; as not only is the constriction close, but the point of junction is 

 small and the parts so fine and delicate that they break with a touch, and nothing but 

 the finest hair can be used in manipulating them. 



At the opposite end of the sacculus from the cornu, namely, at the base of the cone, 

 which is the anterior end, there are two branches which I propose calling the " rami 

 sacculi." These rami are bilaterally paired structures, really diverticula of the sacculus, 

 forming wide tubes springing from the lateral edges of the base (figs. 48, 49, 67, rs) ; 

 then' length is nearly equal to the width of the sacculus, but they vary in proportion iu 

 different specimens, and even on the two sides of the same creature ; their histology is 

 identical with that of the sacculus, and their lumen continuous with it without any con- 

 striction ; they are of about even diameter throughout, and run forward somewhat side- 

 ways and a little downward. The distal ends are almost closed and are rounded. From 

 the distal end of each ramus springs a much smaller tube longer than the ramus 

 (figs. 48, 49, ta); these I propose calling the tubuli annulati, or ringed tubes. They 

 spring from and open into the rami, without any valve or other closing apparatus that I 

 have yet been able to discover between the two ; I mention this because it is not the case 

 in many other species. The histology by no means agrees with that of the rami : they 

 appear to have two tunics, which seem almost, if not quite, detached from each other ; 

 the outer, which is the thinner, is much the looser and more flexible, and is distinctly 

 ringed or wrinkled transversely, the ringing being rather irregular ; this tunic does not 

 pass within the ramus, but stops at or immediately before the point of junction. The 

 inner tunic seems of a closer and more substantial texture, but neither show cellulation. 

 It must not be supposed from the fact of these tubuli being ringed that they are trachea? ; 

 they never by any chance contain air, and they do often apparently contain fluid ; more- 

 over, the ringing is not at all like that of trachea? ; and finally the trachea? of Gamasids, 

 with which they are abundantly supplied, resemble those of most other Acarina? in not 

 presenting an appearance of ringing or spiral threads, although they might probably be 

 made to break up into spirals by properly applied pressure as in the Oribatida?. The 

 ringed tube on each side commences, as before stated, at the termination of the corre- 

 sponding ramus, and it ends, with a more or less trumpet-shaped mouth, in the thin 



