STERELMINTHA. 



40. 



nicating most freely with those of the opposite half. We might 

 be led to imagine such an extraordinary arrangement as the result 

 of some monstrous connexion of two separate creatures, did not 

 observation show that the conformation is perfectly natural and 

 common to all the species. 



Each half of the body of the Diplozoon possesses a mouth and 

 digestive apparatus, 

 a distinct set of vas- 

 cular channels, in 

 which a circulation of 

 the nutritive juices 

 is evident, and more- 

 over contains a com- 

 plete and indepen- 

 dent generative sys- 

 tem ; but in the 

 annexed diagram, 

 (fig. 40,) for the 

 sake of clearness, 

 these are only par- 

 tially shown, the ali- 

 mentary organs alone 

 being seen upon the 

 left portion, whilst 

 in the opposite the 

 organs of reproduc- 

 tion are displayed : 

 the reader, there- 

 fore, will imagine similar parts to exist on both sides of the 

 body. 



These animals, which are of very small size, being not more 

 than two or three lines in length, are found attached to the gills 

 of the bream, (Cyprinus brama,) from which they absorb nutri- 

 ment. They are fixed in this position by two sucking acetabula, 

 resembling those of Distoma, (6, &,) which are seen on each side 

 of the mouths, and also by four oval membranous appendages 

 (m, m) attached to the opposite extremities of the body, upon 

 which likewise suckers are placed, so that at all four extremities 

 the creature is provided with instruments of adhesion. 



(122.) The mouths (a, a) are two orifices of a somewhat semi- 

 circular form, and at the lower margin of each two teeth are per- 



