232 M. A. Stecker on a new Genus of Arachnida. 



precisely the extremely small chitinous layer of the integuments 

 of the body. The finer canals are branched here also ; and 

 the contours at their extremities forming elegant designs are 

 also present*. The chitinogenous membrane or the matrix 

 is slightly yellowish, and, in comparison with the cuticular 

 layer, very little developed. Whilst in the scorpions, many 

 Chernetidse, and the genus Cyphophthahnus there is a very 

 thick chitinogenous membrane, and the secretion takes place so 

 rapidly that within twenty-four hours (therefore nearly in the 

 same time as stated by C. Schmidt f) a considerable chitinous 

 layer composed of spindle-shaped cells is secreted from the 

 matrix, the cell-layer in Gihocelluni is the result of a very 

 limited process of secretion. As in the Chernetid^ and 

 Opilioneaj, so also in Gibocelhini^ the places of insertion of 

 the abdominal muscles, which were characterized by Trevi- 

 ranus as stigmata J, show two rows of scar-like depressions. 

 The two large glandular tubes opening on the back of the 

 cephalothorax in the Phalangiida^, which were observed by 

 Latreille §, Treviranus ||, Meade ^, Tulk **, and Ley dig ft) 

 but first correctly understood by H. Krohn \\, are also pre- 

 sent in Gibocellum. The pigment-layer, however, is dark 

 olive-brown, not, as in Cerastoma cornutum and PhaJangium 

 jparietahi tile-red ; the cells of the epithelium communicate by 

 excessively fine ducts, repeatedly convoluted in the folded 

 intima, with the internal cavity ; the fine ducts issue from 

 the vacuoliform cavities of the individual cells. 



In Gibocellum the cephalothorax is also completely amalga- 

 mated with the abdomen. On its surface there are two roll- 

 like elevations (G), originating between the eyes situated at 

 the lateral margins of the cephalothorax, and continued in a 

 curved line nearly to the middle of the cephalothorax, where 

 they finally disappear entirely ; these seem to represent the 

 horseshoe-shaped cephalothoracic furrow of Cyphophthahnus 

 (Joseph, loc. cit. p. 242), or the so-called " procurva " on the 



* Siebold, Vergleichende Anatomie, p. 520 ; Leydig, loc. cit. p. 384. 



t Zur vergleichendeu Pliysiologie der wirbellosen Thiere. Brunswick, 

 1845. 



X Vermischte Schriften naturh. und phys. Inhalta Bd. i. 1816, pp. 15 

 ct seqq. 



§ Consid(§rations g^nerales sur I'ordi'e naturel des animaux composant 

 les Classes des Crustacea, des Arachnides et des Insectes, &c. Paris, 

 1810. 



II Loc. cit. p. 25. 



51 Annals & Mag. Nat. Hist. ser. 2, vol. xv. p. 395. 



•* Ann. & Mag. Nat. Plist. ser. 1, vol. xii. ; Froriep's * Notizen/ Bd. xxx. 

 (1844) p. 144. 



tt Loc. cit. p. 433. 



\X Archiv fiir Naturg. 18(57, pp. 79 et seqq. ; Ann, & Mag. Nat. Ilist. 

 ser. 4, vol. i. pp. 87 et seqq. 



