A NEW SPECIES OF TREMATODE WORMS BELONGING TO 

 THE GENUS HASSTILESIA FROM RABBITS IN TEXAS 



By Asa C. Chandler 



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



In the upper third of the small intestine of a specimen of Sylvilagus 

 Horidanus alacer, collected at Houston, Tex., were found a large num- 

 ber of flukes which prove to be a new species of Hasstilesia, for which 

 the name Hasstilesia texensis is proposed. 



HASSTILESIA TEXENSIS, new species 



Specific diagnosis. — Hasstilesia; small worms, oval or elliptical in 

 outline, slightly pointed at the ends, 0.55 to 0.86 mm. long, 0.40 to 

 0.53 mm. broad, and 0.24 to 0.33 mm. thick, varying greatly in the 

 proportions of length, breadth, and thickness according to the degree 

 of contraction. The majority of the specimens are ellipsoid in cross 

 section, the mean maximum measurements of cross sections being 0.44 

 by 0.29 mm., but some specimens are relatively thicker and others 

 relatively broader. Fresh specimens appear a dirty rusty white in 

 color, and do not show the three distinct shades described by Stiles 

 and Hassall (1894) in H. tricolor. The entire cuticle is beset with 

 minute spines, from 4/i to lO/i in length, but the spines are much 

 denser on the anterior than on the posterior part of the body. In 

 many whole mounts the spines drop out in the process of fixation 

 and staining and can not be seen. 



The oral sucker is terminal, with the opening anterior or very 

 slightly ventral; it is relatively much larger than in H. tricolor, and 

 broader than long. It measures from 115/x to 132^ in transverse 

 diameter. The ventral sucker is slightly smaller, measuring from 

 105/X to 120/x in diameter; it is further posterior than in H. tricolor, 

 its center being from 0.21 to 0.34 mm. from the anterior end. In 

 most specimens the center is very slightly posterior to the junction 

 of the anterior and middle thirds of the body. In one small speci- 

 men measuring 540/i in length and 450m in breadth the center of the 

 acetabulum is 240^ from the anterior end. 



The digestive tract consists of the oral sucker, pharynx, and 

 intestinal ceca. The pharynx lies immediately behind the oral 



No. 2792.- Proceedings U. S. National Museum, Vol. 75. Art. 21 



40749—29 1 



