310 



ARACHNIDA. 



der, and was thought to contain the terminations of the seminal 

 ducts : the supposition, however, has Fi &' 



been proved to be erroneous, for the 

 palpus is imperforate, and the sexual 

 apertures of the male are situated else- 

 where, but the organ in question is 

 nevertheless apparently used in the 

 process of impregnation, in a manner 

 to be explained hereafter. 



(356.) Both in scorpions and spiders the alimentary canal is ex- 

 ceedingly narrow, presenting scarcely any of those dilatations met 

 with in the digestive organs of insects. This is a natural consequence 

 of the nature of their food ; for, as they live entirely upon animal 

 juices sucked from the bodies of their victims, there could be little 

 necessity for the presence of capacious receptacles for nutritious 

 matter, or for any reservoirs for the accumulation of effete ma- 

 terial. 



In the Scorpionidce there is no stomachal dilatation what- 

 ever : a straight intestine passes directly from the mouth to the 

 anus, situated at the extremity of the abdomen ; and the insertion 

 of the biliary vessels forms the 

 only distinction between its ven- 

 tricular and intestinal divisions. 

 Five delicate caeca are derived 

 from each side of the ventricu- 

 lar portion, and plunge into the 

 centre of a fatty substance in 

 which the alimentary canal is em- 

 bedded. In Spiders, likewise, 

 caeca are appended to the com- 

 mencement of the digestive ap- 

 paratus, and a slight enlargement 

 (Jig. 142, b) may be said to repre- 

 sent the stomach, from which a 

 slender intestine (g) is continued 

 to the anus. As in the scorpion, 

 a large quantity of fat (A) sur- 

 rounds the nutrient organs, and 

 fills up a great proportion of the 

 cavity of the abdomen. Like 

 the fat-mass of the larvae of insects, this substance must, no 



Fig. 142. 



