34 ACADEMY OF NATURAL SCIENCES 



The most eminent of living entomologists, Mr. Latreille, ob- 

 serves* that neither of the authors who have mentioned this in- 

 sect, saw it in its perfect state ; he therefore thinks it probable^ 

 that the larvae to which they had reference, were those of the 

 Musca carnaria [355] of Linnaeus, or some other analogous spe- 

 cies ; for, he adds, all the larvee of (Estrus known, live on quad- 

 rupeds of the order Herhivora and Rodentia. 



Now, although I have not seen the perfect insect, in question, 

 yet my object in this paper is to show, by the aid I think of 

 sufficient data, that there is an Oestrus of South America which 

 must be added to the catalogue of the foes of our kind, fully 

 capable of a notable agency in augmenting the afflictions of 

 humanity, and to prove that this species is altogether distinct 

 from hovis, to which the ingenious Clark was disposed to refer it. 



A few days since, Dr. Harlan presented to me for examination, 

 a small animal preserved in alcohol, that resembled, at first view, 

 a parasitic worm, but, on a slight inspection, it became evident 

 that it was no other than the larva of a species of (Estrus ; he 

 informed me that he had received it from Dr. Brick, who had 

 extracted it from his own leg, during a journey in South 

 America. 



Desc. The form of this larva is clavate, the posterior [anterior. 

 — Leg.] moiety of the whole length being dilated and somewhat de- 

 pressed ; the segments of this portion are armed with transversa 

 series of small, black, horny tubercles, dilated at their bases, near 

 their tips rather suddenly diminishing to a filiform curved hook, 

 pointing forwards with an acute termination ; these series are six 

 in number on the back and sides, placed in pairs, and three in 

 number on the abdomen ; near the posterior [anterior] termina- 

 tion of the body are [357] numerous minute tubercles of the same 

 character with the others, excepting that they conform to no regu- 

 lar series ; the anterior [posterior. — Leg.] moiety of the body is 

 entirely glabrous, cylindrical, or rather elongate conic, of a much 

 smaller diameter than the posterior [anterior] portion, and trun- 

 cate at the tip ; the lips at the posterior [anterior] termination of 

 the body are short, and the intervening fissure of but little width. 



Total length eleven-twentieths ; greatest width more than three- 

 twentieths of an inch. 



* Nouveau Diet. d'Hiat. Nat. article (Estre. 



[Vol. II. 



