98 ENTOZOA. 



tebrated animals, but up to the present hour none have been dis- 

 covered in the human body, although one species has been detected 

 in the anthropomorphous Simiad^P. They are especially abmidant 

 in birds and fishes ; and in the intestines of these vertebrate hosts 

 they anchor themselves to the soft mucous membrane by means of 

 their retractile proboscides. Upwards of one hundred species have 

 been described, and among the more remarkable of these may be 

 mentioned a large species {E. gigas) infesting the hog, and another 

 {E. forrigens) living in the mysticete whale. 



Notwithstanding the great number of Acanthocephala known 

 to exist, the species display a very marked uniformity of character, 

 so much so, that no one has attempted to place them outside the 

 limits of a single genus ; consequently, also, all are included in one 

 family. The classification, therefore, stands as follows : — 



Ord. ACANTHOCEPHALA=Fam. EcHiNORHYNCHiDiE=G-en. Echinorhytichus . 



Echinorhynchiis. — To observe the external and internal anato- 

 mical peculiarities of this genus, we may select as one of the best 

 and most easily accessible forms, the species which abundantly 

 infests the lesser water-newt {Lissotriton functatus). In the 

 accompanying plate (at fig. 1), I have represented a section of this 

 reptile's intestine of the natural size. It has been laid open in such 

 a manner as to display numerous examples of Echinorhynchus anthu- 

 ris; this parasite being constantly found attached to the internal lining 

 membrane of the gut. A male example, highly magnified, is depicted 

 at fig. 2, and shows at the anterior extremity the partially exserted 

 proboscis, furnished with numerous recurved hooks. At the pos- 

 terior end there is a peculiar membranous bursa, first described by 

 Dujardin as the terminal pavilion. This appendage only exists in, 

 and is characteristic of, the male, its function being that of an 

 accessary clasping apparatus to facilitate the performance of the 

 sexual act. The intromittent organ itself consists of a simple 

 curved spiculum which is ordinarily concealed from view, and when 

 not in use is lodged in a sheath which opens externally at the 

 point of the tail in the centre of the cup-shaped pavilion. The 



