292 Mr. Clark'j Ohfervatlom on the Genus Oeflrui, 



When young the larva is fmooth, white, and tranfparent : as it 

 enlarges it becomes browner, and about the time it is full grown it 

 is totally of a deep-brown colour, having numerous dots on its 

 furfacc, difpofed in tranfverfe interrupted lines, paffing round the 

 fegments. Two diftinfl; and different kinds of lines are feen on 

 each fegment: the uppermort: of them is narrower, and confifts of 

 larger dots. Underneath this is a broader hne, and the dots con- 

 fiderably fmaller. The firft are eafily feen, by ufing the lens, to be 

 hooks bent upwards, or towards the tail of the infe£t. See fig. i, a. 



On examining the broader line of fmall dots (fig. i, b) with a 

 tolerably powerful magnifier, they are alfo found to be hooks, but 

 turned in an oppofite diredlion, that is, downwards in the abfcefs, 

 and towards the head of the infedt. 



Thefe hooks, it is probable, are occafionally eredled by the mufcles 

 of the fkin, and according to the feries of them ufed by the larva^ it 

 is raifed or deprefTed in the abfcefs ; and by this motion, and the 

 confequent irritation, a more or lefs copious fecretion of pus is oc- 

 cafioned for the fuftenance of the larva. 



This fingular arrangement of hooks round the body of the 

 larva^, in this inftance ferves the fame purpofe as the legs in other 

 larva:, enabling it to move about in the abfcefs, and to crawl out of ^ 

 it when ripe, and renders the ufe of the tentacula obfervable in the 

 other fpecies not neceflary in this. 



Befide thefe on the furface of the fkin, there are a number of 

 rounded unarmed prominent points, which have a minute depref- 

 fion in the centre, and appear to be tht/piractda, being the external 

 opening of the extreme branches of the air tubes. 



In what manner the pus is received by the larva fornourifliment 

 is not immediately difcoverable. In the upper part of the larva, or 

 that end which is applied to the external opening in the flcin, may 



bfi 



