HARDWICKE'S SCI EN CE-GOSSLP. 



13 



into the horny substance known as chitine. Before 

 entering upon a description of the digestive organs, 

 I must say a few words on the head. This, as 

 viewed from below, is shaped somewhat like a 

 bishop's mitre inverted, having a deep cleft down 

 the centre of its ventral surface, through which 



the oesophagus, the salivary duct, and the several 

 nerves pass. On the dorsal surface, opposite the 

 cleft, is a projecting spur, shown in the drawing, 

 formed by two horny rods connected by membrane, 

 The whole of this portion of the head is internal, 

 being enclosed within the soft body of the creature, 

 the skin of which is attached round it in the line 

 indicated in the figure. The remaining and anterior 

 portion is external, and carries the antennae and the 

 trophi, the eyes being absent, as might be expected 

 from the subterranean habits of the creature. 



Fig. 14. Fatty rete : a, white portion; b, yellowish 

 portion near the anus, showing distinct oily parti- 

 cles, x 50. 



Fig. 13. 



Fig. 12. 



Fig. 11 . The mentum and lower margin of the head from be- 

 neath,— letters as before, x 50. 



Fig. 12. The alimentary canal: sdsd, the branches of the sali- 

 vary duct ; sg s%, the salivary glands; ces, the oesophagus ; 

 ■pr, the proventriculus; cc, the caeca of proventriculus ; 

 st st, the stomach ; xsc, round white bodies adhering to 

 stomach; bt bt, the biliary tubes; si, the small intestine; 

 cce, the caecum ; col, the colon ; tr tr, trachea?, x 10. 



Fig. 13. Section through the proventriculus and stomach, 

 showing the muscular and membranous coats, and the 

 epithelial lining, the latter being indicated by the beaded 

 outline : ee, cast-off membranous coats of stomach-con- 

 tents from the epithelium ; the remaining letters as before, 

 lying loose inside and separating the stomach, x 10. 



Fig. 15. a, Organisms found in stomach (eregarinac?), 

 x 1(10 j 4, organisms in caecum and colon, x 100. 



The cavity of the head is chiefly occupied 

 by the powerful muscles of the mandibles, 

 to the exclusion almost of its legitimate 

 occupant the brain, which lies in the ventral 

 cleft just referred to. The antenna; are 

 single-jointed organs, placed close to the 

 labrum and the roots of the mandibles, and 

 present nothing very remarkable. The trophi, 

 or mouth - organs, consist of the following 

 parts ; viz.,— 1st, the labrum ; 2nd, the 

 labium ; 3rd, the mandibles ; and 4th, the 

 maxillse. The first of these, viz. the labrum, 

 is a thick fleshy organ covering the mouth, 

 beset with hairs on its inner surface. The 

 labium is not so easy to recognize ; I believe, 

 however, that the homy serrated plate, of which I 

 give a drawing, is the mentum : it is connected by 

 membrane with the anterior and inferior margin of 

 the head, which is somewhat similarly serrated. 

 Immediately above it is a minute fleshy eminence, (he 

 rudiment, I think, of the tongue, between wmich and 

 the plate in question lies the opening of the salivary 

 duct, surrounded by a horny ring. The mandibles 

 are stout, slightly curved, and terminate in two 

 blunt points : at their base is a knob-like process, 



