FASCIOLA HEPATICA. 161 



near the middle line of the body, and give off secondary brandies 

 to the sides of the animal. According to Leuckart, the lateral 

 ganglia described by Blanchard do not exist. The cephalic 

 ganglia, however, give off branches to the oral sucker and sides 

 of the head, some of these twigs being probably concerned with 

 the sense of touch. A thin commisural filament connects the 

 two gangha above the pharynx, but throughout the rest of the 

 system the two divisions remain distinct. 



Comparison with Fasciola gigantea. — Before proceeding to the 

 consideration of the eggs and the development of their contents 

 into the embryonic and higher larval trematode conditions, I would 

 direct attention to the differences subsisting between the common 

 liver-fluke and a similar allied form which I discovered some years 

 since in the Hver of a giraffe. Two examples of the species in 

 question are represented in the frontispiece.* If the actual 

 appearances presented by the water- vascular and digestive systems, 

 respectively, in the frontispiece be compared with the diagrammatic 

 representation of the same systems given in figs. 2 and 3 of Plate XI., 

 it will be seen that they correspond in the main, but in the fluke 

 from the giraffe the number of secondary branches rising from the 

 central longitudinal main stems are, in either system, more numerous 

 than obtains in the common fluke. Moreover, independent of the 

 remarkable disparity of size, some of the specimens of Fasciola 

 gigantea being fully three inches long, the relative form of the two 

 species is very different. In all the examples of F. liepatica the 

 lower half of the body is gradually narrowed towards the caudal 

 point, presenting a more or less V-shaped outhne, whilst in 

 F. gigantea the narrowing only commences at a very short distance 

 from the tail end, which in some instances is not only not pointed, 

 but bluntly curved, or even truncated. In certain cases, the posi- 

 tion of the foramen caudate is significantly marked by a notch at 



* The left-hand figure represents the digestive system injected with artificially pre- 

 pared ultra-marine ; that on the right displaying the water-vascular system injected 

 with vermilion. These drawings are from preparations in the author's possession. 



