362 Anatomy and Physiology of the Family Nepide. (April, 
eggs as to fill nearly the whole abdominal cavity. The tubes 
of the ovaries double upon themselves in the first segment of the 
abdomen, the flexure reaching back nearly to the third segment. 
(Fig. 14 2.) 
As already noted, the females of Perthostoma carry their eggs 
upon their backs until hatched, the young then escaping by 
means of a trap door at the top of the egg. The number ofeggs 
borne by any insect is variable ; I counted them in four individ- 
uals with the following results: 207, 185, 184, 183, and other 
females were dredged bearing less than half as many. The eggs 
of Ranatra and Nepa are crowned with sete, two on the eggs of 
Ranatra and six on those of Nepa, while the eggs of Belostom 
and Perthostoma have none. | 
The female generative organs of Ranatra lack the flexure that 
occurs in those of Belostoma, but in other respects are quite sim- 
ilar. Their chief differences may be seen on reference to Figs 
8 and 9, Plate x1, which are drawn on the same scale. 
C. Tue Function oF RELATION. 
To secure a just harmony in the activity of the differs ) 
of the body, a combining organ of some kind is necessary: © 
food must be adequate to meet the waste of the body. betwee? | 
gence to know when food is needed, and to discriminate ies | 
nutritious and innutritious food is essential ; rep Thee | 
regulated to supply enough oxygen, but not too prc at 
and all other processes of animal life must be sete eles f 
tion with each other, otherwise the organs woul >| 
This round of duties, which is performed by the ner fur f 
ee nstitutes the E 
and the muscles, over which it has control, mit ant fun A 
tion of relation, In some respects it is the m oe 
tion, since it directs all the others. 
I. Tue Nervous SYSTEM. 
shrewd 
The insects of this family are keen and heit pat 
their prey, and energetic in procuring 1t, eo weds onsi 
vous condition must be an active one. ieee ganglia have ° 
degree of cephalization, all the abdom! sth others 
vanced to the mesothorax, where they unite es ganglia 
a complex thoracic ganglion. The remaining $ called 
conglomerate masses, one below the eop me the 
cesophageal ganglion, and the other above, “°°” 
i 
