MR. LUBBOCK ON THE THYSANURA. 445 



a small swelling at one end, and a larger oval body at the other (PL XLVI. fig. 39) ; 

 this, however, is not probably the mature form. 



The testis also contained numerous greenish, oval or somewhat quadrate bodies 

 (PI. XLVI. fig. 41), about -0002" in length, and exactly resembling the similar bodies 

 which I fijund in the testes of Chelifer and Obisimn, and which so curiously resemble 

 the spermatozoa of Tolydesmus. 



There were also a number of larger spherical cells (fig. 42), from -0005" to -001" in 

 diameter, and transparent or containing only a few granules. These may perhaps be 

 compared with the similar bodies found in the testis of Oiiiscus. 



The walls of the triangular reservoir are rather thick, and consist of nucleated cells 

 (PI. XLVI. fig. 38). It contains the spermatozoa and the green bright bodies, as well 

 as some other globules, which resemble oil-globules. 



The walls of the accessory glands are also composed of thick cells. They are com- 

 pletely filled by the minute granules, which form an opaque mass. The ductus ejacu- 

 latorius has an apparently chitinous lining, which is strengthened, like the tracheae and 

 some other chitinous parts of Articulata, by transverse ribs, which, in this case, are very 

 delicate. 



The so-called "gastric tube," and the two filaments which proceed from it, are not the 

 least curious part of the anatomy of Smyutliurus. The gastric or, as it may better be 

 called, the ventral tube is situated on the underside of the body, in the middle line, and 

 immediately behind the second pair of legs. From it the animal can project two long, 

 colourless, transparent filaments, which, when extended, are nearly i^th of an inch in 

 length, are somewhat elbowed in the middle, and at the end are covered with small 

 vesicles or " glands," which, according to IS'icolet, secrete abundantly a mucous fluid, by 

 which the whole organ is " continuellement invisque," but which I have not observed on 

 the specimens examined by me. Nicolet gives a figure (pi. 3. fig. 22) of a tentacle, which 

 does not altogether agree with my observations ; but, as he does not mention the species 

 from which it was taken, it is impossible to say that the difi'erences may not be partly 

 specific, though I am not disposed to think that they can all be accounted for in this 

 manner. M. Nicolet observes that the tentacles are " doues d'un mouvement retractile 

 exactement pareil a celui des tentacules oculaires des Limaces ;" but he does not figure nor 

 describe the very curious muscles by which the apparatus is worked, nor has the subject 

 been investigated by any other naturalist. 



In PI. XLVI. fig. 35, 1 give a figure of the whole organ in a state of retraction. At the 

 point a, the basal portions of the two tentacles, b, b, are attached to the wall of the ventral 

 tube ; the tentacle itself is, of course, in this position turned inside out, the outer wall, b, 

 being the inner wall in fig. 36, and the small vesicles seen on the outer wall in that figure 

 being here in the central part of the hollow tube. All the letters in this figure represent 

 the same parts as in fig. 35. At the part / is attached the muscle e, which in fig. 35 lies 

 inside the tube, while here it is necessarily external to it. The point i is the terminal 

 part of the filament when extended ; the numerous vesicles can be seen, in an inverted 

 position, through the transparent walls, and the muscle h, attached in fig. 34 to the inner 

 side of the extreme end, is turned out in the same manner as the muscle i. The point/ 



