110 CONTAGIOUS DISEASES OF DOMESTICATED ANIMALS. 



the body. It is surrounded by four equal symmetrical lips already de- 

 scribed. At the four commissures of these lips may be seen four strong 

 bands or nervures, which unite the membraneous labial circle to the cori- 

 aceous armature of the mouth. This armature, made up of brown chi- 

 tine, has the form of a complete hemispherical capsule or cupule, the 

 thick border of which is divided into symmetrical but unequal lobes. 

 These consist of two largo lateral lobes, each corresponding to a lip, 

 two small anterior ones corresponding to the anterior lip and two small 

 posterior corresponding to the posterior lip. At the opposite and sym- 

 metrical notches at the extremities of the large lateral lobes are in- 

 serted the bands or ligaments which separate or which unite the mem- 

 braneous lips. The bottom or background of the buccal cavity is a 

 true pharynx, to which is attached the superior end of the oesophagus. 

 It is pierced by a round aperture opening into the oesophageal cavity. 

 On the periphery of this opening are disposed six, sometimes seven, radi- 

 ating papillae, hard like the capsule itself, with dorsal cutting edges. 

 They are real fixed lancets, performing a function similar to those of 

 the surgical instrument known under the name of bdellometer of Scar- 

 landiere. 



The oesophagus (Plate 1, Fig. 5, c) is relatively short, extending 

 from the pharynx to the middle of the neck; it is club-shaped and very 

 thick. Its lumen appears to us tetraquetral rather than triquetral, as 

 among other nematoid worms. In fact, the pharyngeal insertion of the 

 tube is conical, i. e., with four, not three, branches (Plate I, Fig. 4, A). 

 The mucous membrane is surrounded by a longitudinal muscular layer, 

 which, in turn, is enveloped by a layer of very stout radiating fibers, 

 longer inferiorly. The whole is inclosed in a structureless membrane. 



The upper extremity of the intestine into which the oesophagus o])ens is 

 very wide. It is continued by a straight, wide, cylindrical tube, lined, in 

 its entire extent, with brownish, distinctly nucleated cellules, and termi- 

 nates in a short oblique rectum, having the form of an inverted cone. 

 The anus is situated at the base of the very short tail which measures 

 only 1. to .2""" (.004 — .OOSinch) in length. It appears to open most com- 

 monly on the dorsal aspect, that aspect which is opposite to the incli- 

 nation of the head and neck or to the vulva. This is due to the spiral 

 twisting of the female body when the uterus is laden with eggs. The 

 anus of the male opens near the notching of the caudal bursa posteriorly. 

 This shows that in the male also the ventral aspect is uppermost, which 

 in the female is indicated by the vulva. In both sexes the anus is very 

 small; and in fact an animal food, made up of the blood of the host, 

 ought to furnish a very small quantity of solid waste. 



Nervous system. — The nervous system of Syngamus trachcalis, like 

 that of the larger number of the higher nematodes, consists of a 

 flattened ganglion forming a collar about the oesophagus, ami giving off 

 fourquite symmetrical cords anteriorly and four jiosteriorly. The former 





