RECENT WORKS ON THE ENTOZOA. 343 



24. Filar ia trachealis, Cobbold. 



25. Trichina spiralis, Owen. 



2(3. Sty'ongylus broncJiialis, Cobbold. 



27. Eustrongylus gifjas, Diesing. 



28. Sclerostoma duodenale, Cobbold. 



29. Oxyuris vermicularis, Bremser. 



30. Dracunculus medinensis, Cobbold. 



31. Dracunculus Loa, Cobbold. 



"We have here uiue Trematode, ten Cestoid, and twelve Nema- 

 tode species. There are no human Acantliocephala or Gordiacea. 



The round worms, as we have said, are not enumerated in the 

 first volume of Leuckart's work. His list of Cestoids and Trema- 

 todes has priority of publication over that of Dr. Cobbold, and there 

 are differences between the nomenclature of the two writers. Three 

 of the human Trematodes admitted by Dr. Cobbold, Leuckart excludes 

 on the ground of having been as yet inadequately observed ; namely, 

 Hexathyridium pinguicola, H. venarum and Tetrastoma renale. The 

 Monostoma lentis of Nordman, considered by Leuckart a doubtful 

 species, is associated by Dr. Cobbold with Distoma ophthalmoTjium. 

 Both, it has been conjectured, are immature forms of the same 

 species, probably D. lanceolatum. "With these exceptions, the two 

 lists essentially agree. Almost the only positive additions made to 

 "VYeinland's enumeration are Dracunculus loa, and the second 

 species of Bothnoceplialus. 



The above certainly appears a formidable catalogue, especially if 

 we bear in mind that some human Helminths present themselves to 

 the naturalist under a variety of conditions, distinguished so from 

 one another, whether in form, structiu'e, or by affecting different 

 organs of the body, that, previous to a knowledge of their life-liistory, 

 they were looked upon as constituting distinct species. Nay, the 

 dissimilar zooids of the same individual have been placed in separate 

 genera and even orders. Here, at least, is a department of zoology 

 with which all of us are intimately concerned. The paragon of 

 animals may without exaggeration boast, how copious and diversified 

 is the fauna which finds scope and verge enough to gratify the 

 fullest parasitic propensities within the widely extended domain 

 of his body politic. Not the number of species only, that of 

 individuals, also, merits his attention. Kiichenmeister assiu^es 

 us, on the authority of Dr. Kleefield of Gdrhtz, that forty 



