32 On Flulces. 



species, is probably represented by the larger of the two vesicles 

 seen at the junction of the lateral ducts leading from the branched 

 organs above described. The smaller sac lying in front is, in all 

 likelihood, an accessory pouch in which the germs become sur- 

 rounded by the yelk-particles or granules ; the essential act of 

 fertilization is, likewise, herein effected at the same time, by 

 the presence of Spermatozoa which have succeeded in gaining 

 access to the pouch. After a while, the perfectly developed eggs 

 descend into the broad uterine tube, and by their numerous pre- 

 sence impart a deep yellowish or orange-brown colour to this 

 organ. The ova themselves are very small, the largest being about 

 the T -^-g- of an inch long, and -g^ of an inch broad. The example 

 here drawn (Fig. 6), was taken from an Amphistoma, which, 

 with many others, the writer obtained from the paunch of a 

 Zebu, formerly living in the Zoological Society's Gardens, 

 Eegent's Park. The illustrations on the opposite side of the 

 plate represent the male reproductive elements, the lower one 

 (Pig. 5) showing the two largely developed testes, which are 

 irregularly divided into five or six lobes ; the latter consisting 

 of numerous smaller lobules. From each of these glands there 

 passes off a duct or vas deferens, the two afterwards combin- 

 ing to form a single channel; this becomes enlarged towards 

 the end, where it constitutes a sheath for the lodgment and 

 protection of the intromittent organ. The small pencillings 

 higher up (Fig. 7) represent the sperm-cells, containing extremely 

 minute Spermatozoa. In the Amphistome, as in most flukes, 

 the external reproductive orifices terminate separately, and 

 near each other, at the anterior third of the body, their position 

 being generally indicated by a smooth, oval-shaped, papillary 

 eminence. 



A nervous system has been described (by Laurer and 

 Blanchard) in Amphistomes. It consists of two so-called cere- 

 bral ganglions representing the brain ; and from each of these 

 there passes off on either side a chain of smaller ganglia, all 

 of which distribute nerve filaments to the skin. As similar 

 arrangements obtain in other flukes, we shall only here further 

 remark that no one has hitherto discovered any organs of 

 special sense in the true Trematodes or Flukes. 



It remains for us further to observe, that the surface of the 

 Amphistome, though quite smooth to the naked eye, is clothed 

 with a series of minute tubercles, which may be readily brought 

 into view under a half-inch object-glass. Beneath the cuticle 

 we find a layer of cellules forming the true skin ; and beneath 

 this, again, there are two, if not three, layers of muscular fibre ; 

 an anterior longitudinal series, and an inner circular set being 

 readily distinguishable. The substance of the body is traversed 

 by bands of cellular parenchyma or connective tissue, wliich 



