254 CLASS viu. 



the peritoneal covering of the intestines in vertebrate animals; 

 next, a muscular coat of longitudinal and transverse fibres ; then a 

 white, smooth membrane, a layer of areolar tissue probably corre- 

 sponding to the tunica propria of the intestine in vertebrates, but 

 which is often beset with minute glands in transverse rows : and 

 lastly the innermost membrane, an Epithelium, that occasionally, as 

 in the muscular stomach of the Orthoptera, is found hard and horny, 

 forming the teeth or sharp plates with which the stomach is armed. 

 In the intestinal canal of Insects several parts are to be 

 distinguished : but it is much to be wished that writers in the 

 names given to them had been careful to preserve greater uni- 

 formity. The first part is the oesophagus, it has often an expan- 

 sion named crop (ingluvies) ; next follows a muscular stomach 

 (ventriculus musculosus, der Kaumagen, le gesier, the gizzard) ; it is 

 found in the Orthoptera and amongst the Coleoptera in the genera 

 Staphylinus, Dytiscus, and the family of the Carabici 1 , and is 

 remarkable for the great development of the innermost coat, for 

 the projecting plates, teeth or hooklets of corneous tissue which 

 serve for bruising the food ; it is usually folded and has a round, 

 more or less spherical, form 2 . Then comes a long cylindrical 

 stomach in which the proper digestion proceeds. LEON DUFOUR 

 names it ventricule chylifique ; RAMDOHR calls it simply the sto- 

 mach, which name appears to me to be sufficient and preferable to 

 the other. This organ is always present, and beneath its termina- 

 tion the vasa urinaria (of which hereafter) are always inserted 3 . 

 To this succeeds a longer or shorter, sometimes (as in the Hemi- 

 ptera) a very short canal, the small intestine (intestinum tenue), 

 which is continued into the short large intestine (intest. crassum), 

 having occasionally a caecum or expanded portion when the con- 

 nexion takes place obliquely and at the side 4 . 



1 LEON DUFOUR has also discovered a muscular stomach in Tomicus typographic . 

 Ann. des Sc. not. iv. p. 108. 



2 RAMDOHR names it Faltenmagen (plicated stomach, omasus), a very ill-chosen name. 



3 MARCEL DE SERRES considered the stomach to be duodenum ; in that case many 

 insects must have no stomach at all. The name of Crop (jabot succenturie) by which 

 STRAUS denotes this part in the Cockchafer is not explicable. 



4 We are indebted to LEON DUFOUR for most of the investigations of the intes- 

 tinal canal in Insects. They were preceded by those of RAMDOHR, who published a 

 work on the subject, (Abhandlungen iiber die Verdauungswerkzeuge der Insecten, mit 

 30 Kupfertafeln, Halle, i8n, 4to). 



