94 ANIMAL PARASITES. 



tumours produced by them, but will find an orifice in the swelling 

 from which a little moisture constantly oozes, and through which 

 the hinder part of the (Estrus is kept in communication with the 

 air. The prognosis is favorable; immediate cure is only possible 

 by incision and the removal, of the (Estrus. 



It has not yet been settled fo what species of (Estrus these 

 larvae belong, and it has even been supposed, as, for instance, 

 Humboldt has done, that there is an (Estrus humanus. We are not 

 at present justified in the latter course. The insect brought by 

 Schomburgk as the parent of this larva, was a Tabanus (a gad-fly), 

 and can by no means be connected with the larva. The com- 

 mon people also still make the mistake of confounding bot-flies 

 and gad-flies. As the matter stands at present, we can only 

 assert that in the last-mentioned cases the (Estrus Ovis cannot 

 come in question, nor the species living in the frontal cavities of 

 the stag. Neither can we have anything to do with the horse 

 bot-fly ((Estrus equi). The species which come under considera- 

 tion here are the (Estrus Bovis, Cervi Capreoli, and Cervi which 

 live under the skin. 



We have here to observe, that the female (Estrus has a horny 

 ovipositor, which slides out and in like a telescope, and bears five 

 teeth at the end. On the one hand it has been asserted that 

 this ovipositor is used as a boring apparatus in burying the eggs 

 at the moment of laying; on the other, that it has not sufficient 

 strength for this purpose. Those who hold the latter opinion 

 think that the eggs are stuck upon the hairs, and that only the 

 larvae bore under the skin. 



The hot of the ox is black, reddish-yellow in front, clothed 

 with black hairs behind, and becomes an inch long in two 

 months. The bot of the stag is distinguished from the pre- 

 ceding by a series of recurved black booklets, which, in conjunc- 

 tion with the larger horny hooks at the mouth, enable the larva 

 to hold fast in the tumour. Of the larva of (Estrus Cervi Capreoli, 

 the last figure has recently been given by Heunig, of Dresden. 

 Reichenbach, sen., names the (Estrus pictus as its parent. The 

 larva itself is yellowish-white, 10" long, and has nine segments, 

 exclusive of the head and tail, like all larvae of (Estrus ; of these, 

 the first seven are beset on the back with rows of very fine 

 reddish-brown spines (in ten rows), which, however, only extend 

 to the fourth segment on the ventral surface. The mouth has 

 two very small,, blackish-brown, horny hooks ; the dorsal surface 



