294 '-^^''' ClarkV Ohfervatiom on the Genus Oeflrus. 



which extends from one extremity to the other, and ferves the 

 double purpofe of ftomach and ititeftine. The inteftinal canal of 

 the larva of the CE. Equi is feen reprefented at fig. 26. 



The apparatus of air tubes in this larva is very Angular, and is 

 reprefented fomewhat magnified at fig. 25. In this fpecies there 

 are only two principal trunks of thefe air vefiels, which are con- 

 nected near their origin by a lateral trunk. From thefe, branches 

 are feen pafling oft* in every dircdlion through the fubftance of the 

 infeft, fome of them to the inteftine, others to the ikin, and a greater 

 number appear to terminate by anaftomofing with each other. As 

 thefe air veflels form a much greater part of the ftru£lure of the 

 larva of the OE. Eqiii, it will be more proper to fufpend our obfer- 

 vations on them till we come to the defcription of that fpecies. 



The larva having arrived at its full growth, effedts its efcape from 

 the abfcefs, by prefllng againft the external opening, which occafions 

 its enlargement by the points prefled upon being gradually ab- 

 forbed. When the opening has thus obtained the fize of a fmall 

 pea, the ArrT^a writhes itfelf through, and falls from the back of the 

 animal to the ground, and, feeking a convenient retreat, becomes a 

 chryfalis. 



With confiderable difficulty I obtained three chryfalides of this 

 infeiSl ; one of which is reprefented at fig. 3. 



Thefe larvae never change or throw off their (kin, the fame 

 ferving them through their whole growth ; and it at length alfo 

 ferves to form the Ihell of the chryfalis. After leaving the abfcefs, 

 and previous to their becoming a chryfalis, they contrail themfelves 

 into much lefs fpace, and afTume a different figure. See fig. 2. The 

 fack which enclofes the larva beneath the Ikin, is formed of a tough, 

 thick membrane, and rough on the infide ; and the pus fecreted 

 J>y it, ,is moflly of a yellow colour. After the exit of the cater- 

 I pillar. 



