170 CH. WARDELL STILES, 



over the zoologist who studies only free livirig animals. The latter 

 has the type locality (namely, the locality where the first speciraens 

 were collected) as a clue to help him in his determinations, but we 

 have besides the type locality, also the host and the organ from which 

 the parasites were taken. If for instance an early author speaks of 

 finding a red worm, nearly three feet long, in the kidney of a dog, in 

 France, we may conclude with a considerable degree of certainty, 

 what form he was discussing, if he mentions a Strongylus, over half 

 an inch long, in the stomach of a sheep in Germany, only a limited 

 nuniber of species can come into consideration, with the chances de- 

 cidedly in favor of Str. contortus. 



It may also be recalled that if a narae is dated 1860, and we 

 find another designation dated 1850, it is by no means impossible 

 that a few years after the change is made, we shall find still a third 

 name for the same species dated 1830. Many medical and zoological 

 publications have not yet been indexed — but when they are, some 

 changes are bound to occur. Let us therefore in all cases, where it 

 is possible, go back to the oldest name for the use of which any 

 reasonable excuse can be found, and thus diminish the chances of a 

 later change. 



5. The relations of the law of priority to type speeimens. 



Looss further raises the oft discussed poiut regarding the type 

 speeimens, and practically advances the vievv that if we admit that 

 the reexamination of these types is valid in determining a species in 

 case the diagnosis or indication leaves us in doubt, we thereby prac- 

 tically contradict the wording of the Law of Priority. He argues that 

 the published diagnosis is accessible to all, but the type speeimens 

 only to a few. The argument appears well founded until exarained 

 critically, and viewed in connection with its consequences. 



The Law of Priority does not relieve an author from using every 

 available means to determine a form. An exceedingly small form 

 cannot be determined, no matter how exact the diagnosis, uuless a 

 worker has a microscope. Not every zoologist possesses this Instru- 

 ment, yet a man would not be justified in rejecting a name because 

 under these circumstances he was not able to recognize a given species 

 by its description. In some cases, a microtome must also be used, 

 yet the man without a microtome is not justified in declining to rec- 

 ognize a form described from sections. Again, not every published 

 description is immediately accessible to every zoologist in the world, 



