270 



COMPARATIVE ANATOMY. 



compensated for by the brandling' of the casca. The Opilionida are 

 provided with a much 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 



m 



V- 



fp 



j- i 



■r J. 



m 



r; 



& 



V 



Fig. liO. Pupa of the same 

 Insect. 



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

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

 E Hind-gut. gs Cerebral ganglion, gi Sub-cesophageal 

 ganglion. u Ventral ganglion. vm Malpighian vessels. 

 C Heart. Q 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 Galeodcs, 

 where it has a ca3cal sac. In the Aranea also, 

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

 is of a considerable width. 



Fig. 13'J. Larva of a & o i n 



Lepidopterous Insect V -'^V. 



(Sphinx ligustri) ; seen . 



from the side. The Mynapoda and lnsecta agree m 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 



