346 CATALOGUE OF THE ENTOZOA 



The classification to which I have adhered in the following 

 catalogue, is the one given by Rudolphi in his * Synopsis,' fol- 

 lowed by Bremser in both his works, and adopted by almost 

 all zoologists since. I cannot see the necessity for the change 

 in the nomenclature of the orders which has been made by 

 Mr. Owen, in his article Entozoa, in the * Cyclopaedia of Ana- 

 tomy and Physiology.' Rudolphi's terms are in a great mea- 

 sure established, having been adopted by almost every writer 

 Upon the subject since his time ; and if the names of fami- 

 lies or orders are to be altered upon trivial grounds, we should 

 be under the necessity of giving up many of the names 

 which have been longest estabUshed ; indeed nothing appears 

 to have a greater tendency to retard the study of Natural 

 History, than the unnecessary multiplication of names which 

 are already too numerous. But in the present instance, I do 

 not think the new names are an improvement upon the old, 

 the latter appear to me to be more expressive, and their 

 having been adopted by the best practical helminthologists 

 is a sufficient reason for retaining them here. 



Rudolphi has arranged the Entozoa in five orders of fami- 

 lies, each of which includes a larger or smaller number of 

 genera. On the present occasion I shall only notice those 

 genera in which I have as yet detected species inhabiting 

 animals natives of this country. 



Commencing with those most highly organized, they are 

 Nematoideay Acanthocejphalay Trematoda, Cestoidea, and 

 Cystica. 



Order I. NEMATOIDEA. 



(Derived from VYifA,a Jilum, and ^100$ forma.) 



The order Nematoidea includes the Entozoa whose organ- 

 ization is the highest ; the body is cylindrical and elastic, 

 more or less attenuated at each extremity; intestinal canal 

 complete, provided with a mouth and anus ; sexes distinct ; 

 commonly oviparous, rarely viviparous. The head is conti- 

 nuous with the body, very rarely separated by a neck, often 

 obtuse and sometimes edged by lateral membranes (what 

 Rudolphi has called winged). The posterior extremity of 

 the body is either sharp or obtuse, often curved. The male 

 is almost always smaller than the female, and the penis, which 

 is either a single or double spiculum, frequently projects ex- 

 ternally. In both sexes the internal organs of generation 

 (the ovaries in the female and the seminal tubes in the male), 

 are in the form of long filaments, which surround the intes- 



