78 Mr. W. Sells' Observations on the G^stridcB. 



August 27. — A fine male. 



And same day raised the operculum of another, and found 

 the imago perfect, and shrouded within a very delicate 

 thin membranous pellicle, interposed between itself and 

 the inside of the strong shell which is formed by the desic- 

 cation and hardening of th.e thick cutis of the larva. 

 The resemblance of the front or face of the head of CEstrus 

 bovis, particularly in the female, to the countenance of the monkey 

 tribe, is very curious and striking ; the short setaceous antennae 

 proceed from two hemispherical naked shining bodies, whose 

 lighter colour in the circumference, and darker hue in the middle, 

 completely simulate a pair of eyes, placed in hollows not unlike 

 sockets ; immediately below these prominences the face is denuded 

 of hair, and has the appearance of a monkey's skin ; then there 

 is a naked ridge which rises in the medial line proportionally 

 higher than the upper part of the nose in the monkey ; all the 

 lower part of the face is very hairy. 



The telescopic structure of the ovipositor in the female was 

 beautifully distinct, especially in a recent state ; it consists of two 

 highly polished cylindrical joints, of an osseous structure, con- 

 nected one with the other, and the larger to the apex of the 

 abdomen by a strong ligamentous tissue : at the aperture of the 

 tube there protruded a soft papilla, being the termination of the 

 muscular and membranous apparatus enclosed within the horny 

 tube, and through which the ova pass securely to the destined 

 place of deposit, which is doubtless, by the infliction of a wound, 

 in the skin of the animal. 



My specimens confirm the correctness of Dr. Leach's conjecture 

 that the insect he took on the heath near Plymouth, and first 

 named (Estrns ericetorum, is, as he afterwards believed it to be, 

 the male of CEstrus bovis. 



