636 THE SHEEP EOT. 



" An old man of eighty years explained to him the fact of the exis- 

 tence of such worms, and pointed out the means of obtaining them by 

 a sack tied about the nose of the sheep, into which they were received 

 on falling from the sinuses, and this way also was employed by Val- 

 lisneri and Reaumur. 



" When young, these larvae are perfectly white and transparent, ex- 

 cept the two horny plates, which are black. As they increase in size, 

 the upper side becomes marked with two transverse brown lines on 

 each segment, the anterior one shorter and narrow than the posterior; 

 and some spots are also seen on the sides. The body consists of eleven 

 segments. 



" I procured, about the middle of June, some full-grown larvae of the 

 (E. Ovis from the inside of the cavities of the bone which supports the 

 horns of the sheep. They are nearly as large as those of the (E. Equi, 

 of a delicate white colour, flat on the under side, and convex on the 

 upper ; having no spines at the divisions of the segments as the Gastri- 

 colae, but are provided with tentacula at the small end. The other end 

 is truncated, with a prominent ring or margin, which serves the same 

 purpose, in an inferior degree, as the lips of the (E. Equi and haemor- 

 rhoidalis, by occasionally closing over, and cleaning the horny plate from 

 the mucus and pus of the membranes, with which it is subject to be 

 smeared and prevented from performing its office. When this margin 

 opens after closing over the plate, it occasions frequently a slight snap 

 from the sudden admission of the air. 



" They move with considerable quickness, holding with the tenta- 

 cula as a fixed point, and drawing up the body towards them. On the 

 under side of the larva is placed a broad line of dots, which, on exami- 

 nation with glasses, appear to be rough points, serving, perhaps, the 

 double purpose of assisting their passage over the smooth and lubri- 

 crated surfaces of these membranes, and of exciting a degree of inflam- 

 mation in them where they rest, so as to cause a secretion of lymph or 

 pus for their food. 



" I have mostly found these animals in the horns and frontal sinuses, 

 though I have remarked that the membranes lining these cavities were 

 hardly at all inflamed, while those of the maxillary sinuses were highly 

 so. From this I am led to suspect they inhabit the maxillary sinuses, 

 and crawl, on the death of the animal, into these situations in the horns 

 and frontal sinuses. 



" The breeds of these, like the (E. Bovis, do not appear confined to 



