483 



I have repeatedly dissected out the intestinal canal without rup- 

 turing the recurrent intestine ; and it may be observed that the 

 structure of the whole digestive organs, as now described, is in 

 accordance with that of the other Homoptera, which would not be 

 the case if M. Ley dig is correct. 



M. Ramdohr examined C. Aini, but his description can hardly be 

 correct, since it is scarcely possible that nearly allied species can 

 differ so entirely in the arrangement of such important organs. 

 Unless Coccus Aini does diifer very much from C. hesperidum, he has 

 made the same mistakes as M. Ley dig, with the addition of having 

 misunderstood or overlooked the hepatic glands, which perhaps he 

 may have mistaken for ovaries. 



The intestinal canal of C. persicce is formed on the same type as 

 that of C. hesperidum. 



Nervous System. 



I do not propose to give a detailed account of the nervous 

 system, and only allude to it in order to mention the great variations 

 observed in different specimens. Figs. 2-9 represent different forms 

 of the nervous system in C. hesperidum, and fig. 10 that of 

 C. persicce : in all the objects are magnified 60 diameters. 



Leydig rightly describes the subcesophageal portion of the gan- 

 glionic column as being reduced to a large mass (fig. 2, &c. A), 

 situated close behind the mouth. This ganglion generally emits, 

 besides the commissure, three large nerves on each side, and its 

 hinder extremity is continued into a still larger nervous column (C), 

 which passes backward for rather more than "014 of an inch without 

 throwing off any branches. It then divides, and after a while each 

 of the divisions again subdivides, so as to give off a rich plexus of 

 nerves to the posterior part of the body. 



The posterior pair of nerves (fig. 2, &c.) always throws off on its 

 inner side, and not very far from its origin, a nerve (F) which I 

 once traced and found to unite with one of the nerves derived from 

 the main central chord. This nerve (F) is always present, but the 

 point at which it leaves the main nerve (B) is very variable, being 

 sometimes as much as '014 of an inch from the subcesophageal 

 ganglion, sometimes quite close to it. Indeed, in more than one 

 instance it arose from the ganglion itself, and not from the nerve B 

 (fig. 3). 



