140 NEW YORK ZOOLOGICAL SOCIETY. 
To the naked eye the sexual differences are readily discernible. 
The female maintains almost throughout a uniform calibre of 
I mm., but at the cephalic end it diminishes to about .5 mm. and 
at the caudal extremity to about 1-100 inch, the extreme point 
being bluntly convex. The oviducts of the female are usually 
crowded with eggs. The largest eggs contain coiled embryos. 
The male parasite is readily recognized by its comparatively slen- 
EMBRYO, 
MAGNIFIED. 
EGG, MAGNIFIED. 
EGG CONTAINING COILED EMBRYO. MALE AND FEMALE, NATURAL SIZE. 
STRONGYLUS FILARIA. 
der body, having a diameter of about 1.2 mm., and also by its spi- 
rally curved tail, which is three or four times twisted upon itself 
with the regularity of a corkscrew. The coiled portion is much 
narrower than the body of the work, gradually becoming atten- 
uated to the breadth of 1-300 inch, the extreme point, however, 
terminating bluntly as in the female. 
Strongylus filaria and Strongylus micrurus are the species of 
nematodes found in the bronchia and lungs of our American elk 
