410 MORPHOLOGY OF THE ABDOMEN IN THE ODONATA 



fourth segment, two segments in front of the strong subintestinal 

 muscle. It is therefore free to move the ventriculus and gizzard 

 through this distance at least. When the muscle is relaxed and 

 the ventriculus is as far caudad as possible the posterior end of the 

 gizzard is on the line between the second and third segments; 

 and as the ventriculus is large, the gizzard is pushed into the 

 thorax when the diaphragm contracts. 



The gizzard projects but a short way into the much larger 

 ventriculus. This is always pear-shaped and with the large 

 end forward. It reaches well into the fifth segment where it 

 enters the Short Intestine after receixdng a whorl of short Mal- 

 pighian tubules. 



The Small Intestine passes into the sixth segment, doubles 

 back upon itself and passes dorsally to join the branchial basket. 

 Its dorsal part expands to form the pr^-rectal ampulla as usual. 



There is nothing peculiar about the branchial 1 asket and the 

 vestibule except the large size of the former. 



The Reproductive System 

 This system has not been as carefully worked out in the larvae 

 of the Libellulinae as in the case of Anax. The positions and 

 stages of development of the gonads in full grown larvae seem 

 to be about the same. The sperm receptacle of the female is 

 usually oval, large enough to lift and crowd forward the nerve 

 ganglion, and in Tramea it was seen to have two small recurved 

 accessary sacs toward its posterior end. The oviducts follow the 

 usual path beneath the sternal muscles. There is nothing of 

 special note regarding the male reproductive system. 



The Nervous Sj'stem 

 (Plate XXIV, figure 13) 

 Due to the stoutness of the body in all of these forms the ganglia 

 are closer together than in the Aeshnids, and the connectives lie 

 well apart. The relative sizes of the gangha have not changed 

 appreciably. The eighth in the female is always saddled upon 

 the enlarging sperm receptacle. 



The Muscular System 

 (Plate XXIV, figures 13, 14, 15, and 16) 

 The organization of the muscles is in certain respects inter- 

 mediate between that of the Aeshnidae and the Zygoptera. The 



