224 PROCEEDIXGS OF THE NATIONAL MUSEUM vor-. 84 



species of Cercorchis inhabiting tliem are the same. From the stand- 

 point of morphology the species from Siren lacertina differs considerably 

 from the numerous drawings and descriptions of the species studied. 



Family TELORCHIIDAE Stunkard, 1924 



Subfamily Telorchiinae Looss, 1899 



Genus CERCORCHIS Luhe, 1900 



CERCORCinS SIRENIS, new species 



Plate 11 



Specific diagnosis. — The mature worms available for study have 

 a length of 0.78 to 1.56 mm and a width of 0.19 to 0.31 nun at the 

 anterior edge of the acetabulum. In thickness they measure about 

 0.11 to 0.14 mm near the acetabulum. Spination is marked at the 

 anterior end. The ends in the fixed specimens taper somewhat and 

 are slightly flattened or rounded. The oral sucker is 0.11 by 0.09 

 to 0.13 by 0.11 mm in diameter. The prepharynx is approximately 

 0.01 mm in length. The pharynx is somewhat oblong and is 0.03 by 

 0.04 to 0.04 by 0.04 mm. The esophagus is 0.02 to 0.03 mm in length. 

 The intestinal caeca end very little cephalad or caudad of the posterior 

 testis. The acetabulum is 0.10 mm in diameter if circular, or 0.12 

 by 0.11 to 0.12 by 0.09 mm in diameter if somewhat elliptical in 

 outUne. The spherical ovary is about 0.06 mm in diameter and is 

 located slightly anterior of the middle of the organism or central in 

 position. The vitellaria are arranged in folUcles and extend from tlie 

 posterior border of the acetabulum to the anterior border of the 

 anterior testis. The posterior part of the vagina, or metraterm, runs 

 ventral to the cirrus sac, the latter crossing over the former. The 

 cirrus sac, including the seminal vesicle and prostate parts, extends in 

 waves from the posterior dorsal border or middle of the ovary to the 

 genital pore, into which it opens jointly with the vagina. The large 

 genital pore is located at the anterior left border of the acetabulum. 

 The ova in a collapsed condition are 13m by 39. 6^ and in the more 

 normal shape 19.8m by 36.3ju to 16. 5^ by 42. 3^. The testes, which 

 are not uniformly spherical, are located near the caudal end and the 

 posterior one is slightly larger than the anterior. The anterior testis 

 measures 0.04 by 0.07 to 0.8 by 0.11 mm and the posterior 0.06 by 

 0.10 mm. 



Host. — Siren lacertina Linnaeus. 



Habitat. — Intestine. 



Locality. — Southeastern United States. 



Type specimens. — U.S.N.M. Helm. Coll. no. 9021. 



Remarks. — Fixation may result in a slight change in the size or 

 contour of the organs as it does in the contour of the body. An 



