214 PROCEEDINGS OF THE ACADEMY OF [Mar., 



TWO NEW SARCOSPORIDIA. 



BY HOWARD CRAWLEY. 



Sarcocystis leporum sp. n. 



The material on which the present study is based consists of the 

 arm and shoulder of a very old male rabbit shot at Bowie, Md., 

 on December 13, 1913. The presence of Sarcosporidia in rabbits has 

 been recorded from time to time in the literature, and there are four 

 specimens of this parasite in the collection of the Zoological Division 

 of the Bureau of Animal Industry, the localities of which were 

 Maryland, Pennsylvania, New York, and Illinois. No descrip- 

 tion of the organism has ever been published, nor has it received a 

 name. With regard to this latter point certain authors have of late 

 assumed that the Sarcosporidia, like other parasites, are in the case 

 of each species capable of dwelling in any one of several hosts, and 

 there is a certain amount of experimental evidence that this is true. 

 Nevertheless, in the event of a duplication of names, it is very easy 

 to relegate one of them to synonymy, whereas it is extremely awkward 

 to be obliged to refer to a parasite as the sarcosporidian found by a 

 certain author in a certain animal from a certain locality on a certain 

 date. Hence it seems best to make a new species, and I propose 

 to call this parasite Sarcocystis leporum. 



In the fresh tissue the parasitic "cysts were visible as short, delicate 

 threads or rods lying in the muscles. They were about two milli- 

 meters long, and the diameter measured in paraffin sections was 

 from 200 to 250 microns. It may incidentally be mentioned, how- 

 ever, that the size of a sarcosporidian cyst is of no diagnostic value, 

 since it is wholly a function of the age, and the cysts of this particular 

 specimen were probably much under the possible maximum size. 



Compared with the infestations seen in rats, mice, and ducks, that 

 of the rabbit here under consideration was very slight, and a casual 

 glance at the flesh would probably not have revealed anything amiss. 

 Data as to how heavily rabbits may become infested are, however, 

 wholly lacking. 



The cysts, in paraffin sections, showed nothing noteworthy. The 

 cyst wall was from 5 to 6 microns thick, and seen under low powers 

 presented the typical striated appearance. Under high magnifica- 



