296 DESCRIPTION OF THE PLATES. 



reproduce this arrangement, which cannot be demonstrated to the 

 unassisted eye. 



/ Salivary bladder. 



g. Gizzard communicating with the chylific stomach, /, through the inter- 

 mediation of a short segment of small calibre. 



h. Whorl of eight caeca at the commencement of the chylific stomach. 



i. Chylific stomach, smooth externally as is the upper half of the homo- 

 logous segment in Gryllotalpa. 



j. Malpighian tubules, in number from twenty-four to thirty; inserted in 

 a zone around the lower end of the chylific stomach. This insertion 

 is unusual, and they generally open into the commencement of the 

 intestine, from which they are developed as outgrowths in Blatta 

 germanica and all Insecta. 



k. First portion of the intestine or ' small ' intestine. 



/. Large intestine or colon ; found ordinarily in its upper part distended 

 with the refuse of the ingesta, and below of smaller calibre, and corru- 

 gated so as to present a beaded appearance. 



m. Rectum showing the longitudinal lines formed by internal ridges sup- 

 plied with numerous tracheae. The ridges thus developed upon the 

 rectum constitute in the larvae of the Libellulidae, together with a 

 valvular apparatus developed from the caudal tegumentary skeleton, 

 their aerating organ. 



n. First abdominal ganglion, closely approximated to the third thoracic, 

 and placed at a slightly greater distance from the second abdominal 

 ganglion. The sixth abdominal ganglion should have been drawn 

 as somewhat heart-shaped, but laterally constricted so as to have 

 the appearance of being made up, as it probably is, of more than 

 one distinct ganglion. The two oviducts pass to their point of 

 fusion from the outside of the angle bounded by the nerves, seen to 

 spring from this ganglion. The sub-oesophageal ganglion is not 

 seen in this figure, being, as always in Insects, in such close appo- 

 sition to the supra-oesophageal or cerebroid ganglion, as to have been 

 sometimes, but inconveniently, described as making up, together with 

 it, a ' brain.' Counting, however, this ganglion whence the man- 

 dibles, maxillae, and labium receive their nerve supply, we find that 

 the entire ventral cord is made up of nine ganglia, the last of which 

 may be taken as representing more than one ganglion. 



o. ' Verticillate ' ovary of right side, consisting of eight egg-tubes, con- 

 nected by a suspensory ligament, which is made up by the fusion 

 of filaments from their respective apices, and is attached to the 

 dorsal region of the thorax. The proximal extremities of the 

 oviducts vary in shape with their state of distension. Hence they 

 have been described in very different terms by different authors. The 



