ME. H. M. BERNARD ON THE CHEENETID^. 419 



occur near tlie genital aperture, which might very easily be 

 mistaken for spinning-glands. To these we shall return. 



The fine chitinous ducts of the true spinning- glands open, in 

 Ohisium, on a blunt prominence at the back of the movable 

 digits of the mandibles ; they can be seen running down these 

 limbs, about seven in number, and not more than 1 /n in diameter 

 (see fig. 2 a, d). These seven or more ducts lead into as many 

 somewhat coiled cylindrical reservoirs (6 fi in diameter), which 

 again gradually pass into the secreting portions of the glands. 

 These, the glands themselves, run more or less straight back- 

 ward immediately under the dorsal wall of the body, sometimes 

 reaching into the second or third abdominal segment. The cells 

 composing the wall were so packed with granules that I entirely 

 failed to discover any nuclei. In glands which appear to be 

 degenerating, the granules were fewer and the cells seemed to 

 be breaking down. In these cases a fine staining-reticulum 

 can be seen running among the granules ; this and the trace of 

 staining round the periphery of the gland are the only signs of 

 protoplasmic arrangement I could perceive, besides the fine 

 radially arranged lines bounding the separate cells. These 

 glands are accompanied by a number of exquisitely fine tracheal 

 tubules. The homology between these spinning-glands and the 

 poison-glands of the Araneids is obvious. I do not think that 

 the absence of the very specialized muscle-layers in the latter is 

 a point of importance. 



These glands seem to be subject to periodical variations ; 

 Croneberg found them most fully developed in summer. One of 

 my specimens shows no other trace of them than their chitinous 

 ducts in the mandibles. 



The extremely thin and transparent combs on the mandibles, 

 said to be used as manipulators of the silk, are formed by folds 

 of the external hard refractive layer of the chitinous cuticle. 



The abdominal glands open by median papillae. The anterior 

 papilla projects from the anterior edge of the second segment, 

 and opens under the genital operculum. The posterior papilla is 

 similarly situated at the anterior edge of the third segment, and 

 is covered by the segmental fold of the second segment. Gihho- 

 cellum has spinning-glands on the second abdominal segment, 

 and Stecker suggests their existence on the third segment also. 



Stecker describes the glands in Gihhocellum as opening 

 through a number of minute papillae, in which case they would 



