270 



COMPAEATIVE ANATO^IY. 



compensated for by tlie branchiug of tlie caeca. Tlie Opilionida are 

 provided with a mucli greater number (about thirty), and a median 

 pair is provided with secondary appendages. 



The portion of the mid-gut behind the stomach varies in length ; 

 when it is long it is widened out towards its end, and is separated 



r— 



u,' 



// 1 



/^' 



Fig. 110. Pupa of tlie same 

 Insect. 



Fig. 1 11. Its imago, flleacl. 2, 3, 4 Thoracic segments. 

 5-13 Abdominal segments. V Fore-gut. M Mid-gat. 

 E Hind-gut. gs Cerebral ganglion, r/i Sub-CESophageal 

 "•angliou. u Yentral ganglion. vm llalpighian vessels. 

 ° C Heart. G Generative organs (after Newport) . 



off from the hind-gut by a constriction ; this 

 latter is almost always widened, it is pretty 

 long in the Scorpionea, but shorter in Galeodes, 

 where it has a ctecal sac. In the Aranea also, 

 and in the Acarina, the hind-gut (Fig. 137, r) 

 is of a considerable width. 



Fig. 139. Larva of a 



Lepidopterous Insect 



(Sphinx ligustri) ; seen 



from the side. 



§ 210. 



The Myriapoda and Insecta agree in the 

 mode of arrangement of the chief tracts of 

 their digestive system ; which at the same time closely resembles 

 ■what obtains in Peripatus. Of the three divisions of the digestive 

 tube the fore-gut only prepares the food, and the mid-gut has the 

 principal share in digesting it. As? a rule it forms the longest 



