182 ON THE STICK-INSECT. 



EXPLANATION OF THE PLATES. 



Plate XXVIIl. 



Fig. 1. Alimentaiy canal of Bacillus rossii. Md., mandibles; Ph., pharynx; 

 M., muscles of the pharynx; (E., oesophagus ; Cr., crop; Gmj, anterior 

 reg'ion of the mid-gut ; Gmj, posterior region of the mid-gut ; F., dorso- 

 longitudinal furrow in which several longitudinal muscles are congregated ; 

 C, rudimentaiy coeca of the mid-gut; Ta., tubular appendages of the 

 mid-gut with their filiform prolongations ; Mt., Malpighian tubes ; 

 Is., small intestines; E., rectum, with the rectal longitudinal folds Rf. 



Fig. 2. Portion of the external wall of the crop. Mc, circular muscle; Mo., band of 

 oblique muscle fibres, of which there are six, extending longitudinally along 

 the oesophagus and crop, and displacing in great measure the ordinary 

 longitudinal muscles ; Rmc, circular muscles reflected to show one of the 

 bands of oblique fibi"es. 



Fig. 3. Crop and anterior part of the mid-gut. Cr., crop ; Gn., ganglion ; Tr., trachea ; 

 Gm., mid-gut; C, rudimentary cKca of the mid-gut; FL, longitudinal 

 muscles grouped together in the dorso-longitudinal furrow; Ml,, longi- 

 tudinal muscles lying outside the furrow. 



Plate XXIX. 



Fig. 4. Transverse section of the crop. Mc, circular muscles; Ml., longitudinal 

 muscles; Pm., peritoneal membrane; E., epithelial cells which secrete the 

 chitinous lining Ch. 



Fig. 5. Longitudinal section of the posterior region of the crop and anterior region of 

 the mid-gut. Mc, circular muscles of the crop ; C, rudimentary digestive 

 cseca; Mg., mucilaginous globules secreted by the epithelial cells of the 

 cseca as also by those of the mid-gut. In the mid-gut these globules 

 occupy the space between the epithelial layer and the peritrophic mem- 

 brane. They are not included in the figure. ML, longitudinal muscles ; 

 Ch., chitinous lining of the crop secreted by the chitinogenous cells cc, 

 extending with the " valvular " prolongation into the mid-gut; Mp., peri- 

 trophic membrane; E., epithelium of the mid-gut with Cb., the ciliated 

 border; Ovi, primary dorsal oesophageal " valve " with the con'esponding 

 ventral small " valve " Ov,a. 



Fig. 6. Transverse section of the anterior region of the mid-gat. E., epithelium ; 

 Cb. , ciliated border; Ej, epithelium of an adjacent fold which has also been 

 cut through ; Mlj and MI2, the longitudinal muscles of the dorsal and 

 ventral longitudinal grooves of the mid-gut; Mc, circular muscles; 

 Mp., peritrophic membrane; Pm., peritoneal membrane; Mg., globules of 

 mucilaginous secretion. 



Plate XXX. 



Fig. 7. Transverse section through the junction of mid- and hind-guts. E., epithe- 

 lium ; Ml,, longitudinal muscles; Pm., peritoneal membrane; Mp., 

 peritrophic membrane; Ch., chitinous lining of the hind-gut; Mt., Mal- 

 pighian tubes ; Cd) and Cdj, common ducts of several Malpighian tubes. 



Fig. 8. Transverse section of the rectum. E., band of large epithelial cells, of which 

 there are six ; between each two bands there is a non-epitheliated 

 interspace I, where the chitinous intima Ch. becomes con-ugated and is 

 ^-osely applied to the basement-membrane Mb.; Tr., trachea; M., muscular 

 layer. 



Fig. 9. Section through small intestine at the orifice of the rectum. F., one of the 

 six projections or valves which shut off the small intestine from the rectum ; 

 E., epithelium secreting the chitinous intima Ch. ; Mc, circular muscle; 

 Ml., longitudinal muscle; Tr., trachea. 



