13 ANIMAL PARASITES. 



toneal coat and readily detached, which forms a small longish 

 knot, ] li"' Par. = 2J 3'37 millim. in length, imbedded hori- 

 zontally or perpendicularly in the liver, and projecting a little 

 beyond its level. The animal, which measures about 3'2 millim. 

 = 1*4'17"' Par. in length, has usually a lunate curved form in the 

 human subject; it is calcified, and of a yellow colour, and adheres 

 so firmly to the capsule, that the animal can only be freed from 

 it uninjured, with great difficulty, as Van Beneden found mother 

 Lingua tnl&. The animal is usually found on its side ; its convex 

 margin represents the back, its concave one the belly ; the head, 

 O76 mill, in breadth, as well as the tail, which diminishes 

 towards the extremity to a breadth of O15 mill., are both 

 rounded off. Constrictions are exhibited at the margins, pro- 

 bably caused by death. The body is about 0'84 mill, in breadth. 

 The deposition of calcareous matter takes place in the interior of 

 the body after death ; by the application of muriatic acid and 

 moderate pressure, the animal becomes transparent, with evolution 

 of carbonic acid. 



The skin, which in the uninjured animal brown and opaque, 

 and in separate fragments colourless, limpid, and homogeneous, 

 is beset throughout with series of spines running round the 

 animal (60 80 in all), each of which bears about 160 acute, 

 slender, conical, flexible, glassy spines, directed backwards, and of 

 different lengths in different parts, but on an average about 

 0-02 3 mill, long. In the free space of about 07 mill., between 

 two rows of spines, we see at somewhat wider intervals rows of 

 small, dark rings with double outlines = spiracles = Stigmata 

 respiratoria (Diesing), so that two stigmata occur for 3 4 spines. 



Of internal organization nothing can be detected from the cal- 

 cification of the animal. The most important point is the 

 knowledge of the apparatus of hooks, which I first detected in 

 the Linguatula ftrooc of the ruminants, and Zenker afterwards 

 again found upon his preparations, which Van Beneden also can 

 confirm as regards Zenker's preparations. 



In the middle of the forehead, and near its anterior margin, 

 there is, in the first place, a yellowish chitinous oval ring, of 

 about the form of uninjured eggs of Tcenia dispar ; at each side 

 of the oral ring lies a pair of yellowish, rather large, strongly 

 curved hooks, recognisable even by the common lens, which 

 resemble the claws of large tapeworms, such as T&nia crassicollis, 

 if imagined without stems, and the bases of which are broad, 



