INTERNAL ANATOMY OF THE GAMASID.E. 301 



may for the moment he either wliolly closed or slig-htly or considerahly open ; wlien open it 

 forms the entrance to a much smaller pyrit'orin sac (tigs. i.S, 49, cs), joined to tli(; first hy a 

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

 first, hut 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 broader end of the coruu 

 is toward the sacculus. but it tui-ns almost perpendicularly downward (fig. i!)j, so that 

 its apex is the lowest part ; this again is not absolutely closed, only constricted, but the 

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

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

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

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

 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 nothino- 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 ai-e two branches which I propose calling the " rami 

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

 forming wide tulies springing from the lateral edges of the base (figs. 48, 49, 07, rs) ; 

 their length is nearly equal to the width of the sacculus, but they vary in proportion in 

 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 tlian 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 otlier 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 liistology by no means agrees with that of the rami : tliey 

 appear to have two tunics, which seem almost, if not quite, detaclied 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 traclieas ; 

 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 trachete ; and finally the tracheae of Gamasids, 

 with which they are abundantly supplied, reseml)le those of most other Acarina^ in not 

 presenting an appearance of ringing or spiral threads, although they might ])rc)bably ])e 

 made to break up into spirals ])y properly applied pressure as in the Oribatidte. 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 



