THE PERITROPHIC MEMBRANE 



818 



Proventricular valvule. Gehuchten also describes in Ptychoptera what he 

 calls "the proventricular valvule," stating that it is "a circular fold of the 

 intestinal wall" (Fig. 316, vpr). He claims that it has not before been found, 

 the "proventricular beak" of Schneider being regarded by him as the cesoph- 

 ageal valvule. 



The peritrophic membrane. -7- This membrane appears first to have 

 been noticed by Ramdohr in 1811 in Hemerobius perla. It has been 

 found by Schneider, who calls it the " funnel." On the hinder end 



white glands; mat, urinary vessels; iff, small intestine; f/i, large intestine; r, rectum; A, the 

 proventriculus in which the hinder end of the oesophagus extends as far as the chyle-stomach. 

 , longitudinal section of the proventricular region ; sph, muscular ring or oesophageal sphincter ; 

 ppr, wall of the proventriculus ; e, circular constriction dividing the cavity of the proventriculus 

 in two ; vpr, circular fold of the wall of the mid-intestine forming the proventricular valve ; <#, 

 oesophageal valve. After Gehuchten. 



of the fore-stomach, he says, the cuticula forms a fold enclosing the 

 outlet of the fore-stomach, and extending back like a tube to the 

 anus. This " funnel," he adds, occurs in a great number of insects. 

 It has been found in Thysanura, but is wanting in Hemiptera. In 

 the Coleoptera it is absent in Carabidae and Dyticidae. It is gener- 

 ally present in Diptera and in the larvae of Lepidoptera, but not in 



