TREMATODA 15 



Distoma hcpaticum ; but the title is both incorrect and inappro- 

 priate. The proper generic appellation of this parasite is 

 Fasciola, as first proposed by the illustrious Linneus (1767) and 

 subsequently adopted by F. Miiller (1787), Brera (1811), Ram- 

 dohr (1814), and others. Unfortunately Retzius (1786) and 

 Zeder (1800) changed the generic title without good cause, 

 and the majority of writers, following their authority, refused 

 to employ the original name, although a consideration of the 

 distinctive types of structure severally displayed by the genera 

 Distoma and Fasciola fairly demanded the retention of the 

 Linnean title. In later times M. Blanchard (1847) strongly 

 advocated the original nomenclature, and I have myself con- 

 tinually urged its adoption. On somewhat different grounds 

 Professor Moquin-Tandon followed the same course. 



In the sexually mature state the liver fluke commonly 

 measures three fourths of an inch in length, occasionally reach- 

 ing an entire inch or even sixteen lines ; its greatest breadth 

 also varying from half an inch to seven or eight lines trans- 

 versely j body very flat, presenting distinct dorsal and ventral 

 surfaces, frequently curled toward the latter during life ; upper 

 or anterior end suddenly constricted, produced and pointed 

 in the centre, forming the so-called head and neck ; posterior 

 extremity less acuminated, sometimes rounded, or even slightly 

 truncated ; margins smooth, occasionally a little undulated, 

 especially towards the upper part ; oral sucker terminal, oval, 

 rather smaller than the ventral acetabulum, which is placed 

 immediately below the root of the neck ; reproductive orifices 

 in the middle line, a little below the oral sucker ; intromit- 

 tent organ usually protruded and spirally curved; a central, 

 light-coloured space, covering two thirds of the body from 

 above downwards, marks the region of the internal male re- 

 productive organs, being bordered on either side and below by 

 a continuous dark band, indicating the position of the so-called 

 yelk-forming organs ; a small, brown-coloured, rosette-like 

 body situated directly below the ventral acetabulum, marks 

 the limits of the uterine duct ; a series of dark lines, branching 

 downwards and outwards on either side, indicate the position of 

 the digestive organs ; general color of the body pale brownish 

 yellow, with a slight rose tint. The surface of the body, though 

 smooth to the naked eye, is clothed throughout with small 

 epidermal spines which diminish in size towards the tail. 



If any argument were necessary to show how desirable it is 



