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F a 
254 Anatomy and Physiology of the Family Nepide. (March, 
From the colon a large czecal pouch extends forward, beneath 
the intestine, reaching in its ordinary condition to the middle of 
the fourth ventral segment. This is the cecum. It is sometimes 
so distended with air as to reach even to the thorax, and to give 
a bloated appearance to the usually flattened ventral surface of 
the insect. This organ probably plays the same part as the air 
bladder of some fishes, serving as a natatory vesicle. I have 
often seen these insects come to the surface and forcibly exp! 
the air from the cecum. When the abdomen is just below the 
surface, the water is thrown upward in jets by the discharged 
air. I have also noticed the larvz of Belostoma, when irri i 
throw from the anus jet after jet of a strong smelling, light-greet 
ish fluid, the propulsive force of which probably comes from tit 
cecum, | 
Frequently when the insects have died in water, the cæcum 
naturally white, is found swelled and of a dark-blue or livit 
color. From the large number of cases in which this has beet 
observed, I think that it is due to some disease. The chief 
ferences in the alimentary canal of Belostoma and Ranatra m 
_ be seen by comparing Figs. 3 and 5. e 
Method of taking Food—tIn order to understand how — ; 
sects take their food, we must first study the boda ; 
or the beak. This is a three-jointed tubular structure a 
from the modified mouth parts. All masticatory pane 
obliterated, the labium is elongated and folded upon itself vitit 
ing a sort of trough, which is nearly closed at the topi 
this the maxillæ and mandibles are found modified ee 
bristles which, before entering the trough, pass through peak 
made from the labrum. This sheath projects into the > ee 
trough, from above (Fig. 2). and te 
By the action of these bristles the prey is punctured r 
food-juices brought to the real sucking organ, the tine, iat? 
This is a stiff chitinous trough, roofed by a plate "e pt of this 
which the cesophagus enters from behind. The ene 
trough extend much above the roofing, as shown 10 “adie of ™ | 
tion of the apparatus (Fig. 7); from the elevated mi attache 
roof chitinous threads originate, to which muscles a into Qo 
These extend upward, first in one sheet, then Ss are 
parts, one going to the left the other to the ee rid 
tached to the integument of the head. There is ROT” 
