ART. 1 TREMATODE PARASITES OF BIRDS LINTON^ 33 



Larus delawai-ensis. 



1914, January 21. 3; lengths 8, 0, and 11 mm., in formalin. Di- 

 mensions, balsam: (1) Length 6.88; di- 

 ameter, anterior 0.91, at level of testes 1.09; 

 (2) Length 7.8; diameter, anterior 0.91, at 

 level of festes 0.84 ; largest ova in each about 

 0.12 by 0.07. Measurements of sagittal sec- 

 tions: Diameter of oral sucker 0.081, 

 pharynx 0.066; ventral sucker, length 0.114, 

 breadth 0.075; ova, average, 0.114 by 0.072. 

 (Cat. No. 7953, U.S.N.M.) 



EXPLANATION OF PLATES 



a. ventral sucker. o. ovary. 



h. bur.sa. oe. esophagus. 



c. cirrus. P^i- pliaryux. 



cp. cirrus-pouch. »9- shell gland. 



ej. ejaculatory duct. «'•• seminal receptacle. 



ex. excretory vessel. «^"- seminal vesicle. 



g. genital pore. ^- testis. 



gd. germ duct. •"• uterus. 



h. holdfast organ. '^^- ^^^ deferens. 



i. intestine. 'VQ. vitelline gland. 



I. Laurer's canal. yd-, yolk duct. 



m. metraterm. yr. yolk reservoir. 



Unless otherwise stated, sketches were made with the aid of the camera 

 lucida from balsam mounts. 



Plate 1 



Haematotrephus fodiens, new species, from Gavia immer 



Fig. 1. Ventral view of free individual; length 11 mm. The dark-brown, 

 opaque material, which filled the intestine, is not represented in the 

 sketch. 



2. Anterior end of same, enlarged ; length of pharynx 0.10 mm. 



3. Worm from a pedicelled cyst on the serous coat of the pancreas. 



4. Anterior end of same ; length of pharynx 0.06 mm. 



5. Portion of body of same in vicinity of genital pore; diameter 0.14 mm. 



6. Posterior end of rami of intestine of same. 



Plate 2 



Psilostomum plicitum, new species, from Larus argentatus 

 Fig. 7. Ventral view ; length 1.61 ram. 



Psilostotnum Uneatiim, new species, from Lartis argentatus 



8. Ventral view ; length 3.78 mm. 



Psilostomum varium, new species, from Gavia immer 



9. Ventral view ; length 1.54 mm. 



Petasiger nitidus. new species, from Colymbus auritus 

 10. Ventral view ; length 1.75 mm. 

 70841—28 3 



