2 PROCEEDINGS OF THE NATIONAL MUSEUM vol.74 



eter. and is joined to the esophagus by a short slender constriction. 

 The nerve rin«]j surrounds the esophagus about 90/t from the anterior 

 end of the luxly. The excretory pore opens ventrally To/x caudad of 

 the esoi)ha<real bulb. The cervical papillae are situated 172 to 214|U, 

 from the anterior end of the body. The lateral alae ari.se imme- 

 diately caudad of the cervical j^apillae and extend to within a sliort 

 distance from the cloacal ai)erture. ' The tail is lonsr and slender, and 

 terminates in a fine point. (Fig. 3.) There are two narrow, sym- 

 metrical bursal alae and three pairs of caudal papillae, one pair pi'e- 

 anal, one pair adanal, and one pair postanal; the postanal papillae 

 are large and pedunculated, and support the caudal alae. The clo- 

 acal aperture is situated on a slight prominence 340 to 43.'')/x f'-om 

 the end of the tail. Immediately caudad of tiie cloacal aperture 

 there is a small rounded prominence which bears six small spikelike 

 projections. The spicule is simple, slightly curved, and 156 to lOO/x 

 long by 18/x, wide at the base. The gubernaculum is 95 to llO/x long, 

 directed transversely, and is provided at its distal end with a barb- 

 like hook. (Fig. 4.) The ventral surface of the body bears three 

 large, finely striated bosses or mamelons. The most caudad of these 

 prominences lies 25(V in front of the cloacal aperture and is 156 to 

 18T/X. long; the second lies 140 to 155/i, anterior of the first and is 125 

 to 155/x long; and the third is 95 to 125/x anterior of the second and 

 is 125 to 140)Li long. 



Female 11 to 14 mm. long and with a maximum width of 357 to 

 430/x. The esophagus is 435/x long by 45/a wide at the anterior end and 

 increases to 98/i, in width at the posterior end. The esophageal bulb 

 is llT to 310/1, wide. The nerve ring surrounds the esophagus about 

 120/1 from the anterior end of the body. The cephalic dilation is 

 120 to 170/x wide in outside diameter. The cervical papillae are sit- 

 uated 260 to 280/1 from the anterior end of the body. The excretory 

 pore is situated about 4T0/i caudad of the union of the intestine and 

 esoj^hageal bulb. The lateral alae begin at the cervical papillae and 

 extend to the posterior end of the body. The anus is situated 3 to 4 

 mm. from the tip of the tail. The vulva is situated 1.6 mm. from the 

 anterior end of the body. (Fig. 5.) In immature specimens the 

 vulva is covered with a broAvnish colored plaque: in gravid specimens, 

 however, the vagina is protruded. Eggs oval, flattened on one side, 

 and 96 to 98/i long by 28 to 38/i wide. 



Host. — Glauco7nj/s volans volans. 



Location. — Cecum and colon. 



Locality. — Falls Church, Va. 



Tijpe speclmem. — United States National INIuseum Helmintho- 

 logical Collections No. 27827; paratypes No. 27793. 



/Si/phacia th&inpsoni resembles S. obveTafa (Eudolphi, 1802), the 

 type of the genus, in body form and in the number of ventral mame- 



