THE HEMIPTEROUS GENUS BELOSTOMA. 63 



Perthostoma rise to the surface of the water, protrude its abdomen, and squirt a 

 stream of water from the anus for a considerable distance, and then apparently take 

 in a supply of air and disappear. 



The anus is a valvular opening, at the extremity of a prolongation of the abdomen, 

 situated superiorly and considerably posterior to the genital orifice. The anal 

 prolongation is smooth, triangular at its extremity, and grooved longitudinally on its 

 inferior surface, where it forms the entrance to the generative apparatus. In the 

 female it is somewhat shorter but broader than in the male. 



The salivary apparatus. — As in all Hemiptera, the salivary apparatus is complex. 

 The salivary glands are four in number ; two of these are long, and extend backward 

 as far as the commencement of the abdomen ; the others are about one-fourth as long. 

 They lie upon each side of the oesophagus, into the commencement of which they 

 empty, each by a distinct duct. In structure they are of the highest order, being 

 conglomerated. At the head of the longer pair of glands there are placed two small 

 vesicles, side by side, communicating with the duct, and probably serving as 

 reservoirs for the secreted saliva. Besides these, on each side of the oesophagus, 

 there is situated a sigmoid coecal pouch which opens by a narrow duct into the 

 commencement of the oesophagus, in the vicinity of the termination of the salivary 

 ducts. These either elaborate some peculiar fluid or serve as reservoirs to saliva 

 secreted by the proper glands. 



Biliary tubes. — These are four in number ; they are long, much contorted, and lie 

 closely applied against the intestinum tenue. They join the intestine at the junction 

 of the duodenum and ileum, and are connected to each other in pairs at the distal 

 extremity. 



GENERATIVE APPARATUS. 



Male : The testes are placed at the anterior part of the abdominal cavity, one on 

 each side of the stomach. They are irregularly rounded masses, about two lines in 

 diameter, and are composed of a single long convoluted tube. From the testicle 

 passes off the vas deferens, at first narrow, it gradually enlarges as it passes 

 backwards, is a little contorted, and finally joins the one of the opposite side to form 

 the ductus ejaculaiorius, which is a short tube, joining at its other extremity the 

 penis. 



The penis in a state of rest, is contracted within a sheath formed by the anal 

 prolongation superiorly, and a triangular, shorter body inferiorly, which I will call 

 the genital prolongation. When projected, the penis is found to be an articulated 

 organ, three lines in length and curved inferiorly. At its extremity it divides into 

 two parts : an upper, in the form of a hook ; the lower, spoon-shaped, and between the 

 two exists the urethral orifice. 



