SOME PAKASITIC ROUND WORMS OF THE RABBIT 

 WITH DESCRIPTIONS OF TWO NEW SPECIES. 



By Asa C. Chandler, 

 Of the Biological Laboratory, Rice Institute, Houston, Texas. 



In the course of parasitological examinations of domestic rabbits 

 kept in the animal house of the Rice Institute biological laboratory, 

 it was found that nearly every specimen was infested by trichostrongy- 

 lid worms, and in some instances three different species were present 

 in considerable numbers at the same time. The fact that immature 

 specimens of all three species were present in some of the rabbits 

 Avhich had been kept in the animal house for from six weeks to two 

 months, would seem to indicate that the infection, in some instances 

 at least, was acquired in the animal house. Since all of the rabbits 

 which have been kept in the house have been obtained in Texas, from 

 breeders either in Houston or New Braunfels, it is probable that the 

 worms originally came from Texas. 



One of the species, and the one found in greatest abundance and in 

 the largest number of individuals, is Trichostrongylus calcaratus. 

 described by Ransom (1911) from cotton-tail rabbits, Sylvilagiis 

 iloridanus maUums, in Maryland. A number of young individuals 

 of this species were found. The males, up to a length of about 3 to 

 3.5 mm., have the posterior end of the body terminated in a bulb 

 with a conspicuous spine on the postero-dorsal extremity of it (fig. 

 1 ) . Within the bulb the bursa of the adult develops, the body then 

 drawing away somewhat from the larval cuticle, as shown in the 

 figure. No doubt the final moult takes place shortly after this. 



NEMATODIRUS LEPORIS, new species. 



Plate 1, figs. 2-5. 



Specific diagnosis. Long slender worms of small size, blood red 

 when freshly removed. Inflated cuticle of neck asymmetrical, and 

 conspicuously striated. 



Male 8 to 13 mm. long with a maximum diameter of from 95 to 

 135 [x. Esophagus 400 to 500 ^ in length. Bursa (fig. 3) well ex- 

 panded, its breadth (250 [;.), greater than its length (210 [x), an 



No. 2553.— Proceedings U. S. National Museum, Vol. 66, Art. 16 



80092 — 24 1 



