24 PROCEEDINGS OF THE NATIONAL MUSEUM vol.75. 



MICROBILHARZIA, new genus 



Generic diagnosis. — Schistosominae : Male longer than female. 

 Gynaecophoric canal well developed, commencing in front of the 

 acetabulum. Suckers present in both sexes. Digestive tract similar 

 to that of Schistosoma. Testes 18 to 20 in number, arranged in two 

 irregular rows in anterior half of body. Genital pore situated about 

 midway between acetabulum and the anterior testis. Female slender, 

 almost cylindrical anteriorly, flattened posteriorly. Ovary loosely 

 spiral, slightly pre-equatorial in position. Uterus long and contain- 

 ing a single &gg. Vitellaria occupy about one-half of body length. 

 Larva unknown or unrecognized. 



Type species. — Microhilhursia chapini^ new species. 



MICROBILHARZIA CHAPINI, new species 



Figures 37-38 



Synonym. — rnitliohilliarzia species Chapin, 1924, p. 208. 



Specific diagnosis. — Microhilhafrzia : 



Male 3.27 to 4.25 mm. long by 626|U, wide. Anterior part of body 

 short, subcylindrical ; posterior part long and with the lateral edges 

 infolded, forming a deep gynaecophoric canal which originates ante- 

 riorly a short distance in front of acetabulum and extends to pos- 

 terior end of body. Cuticle lacking (apparently due to maceration) 

 in all specimens available for study. Oral sucker subterminal, 152ju. 

 in diameter; acetabulum pedunculated, ITS^a in diameter, situated 

 43Tju, caudad of oral sucker. Esophagus simple, bifurcating in front 

 of the acetabulum as in other schistosomes; intestinal ceca sinuous 

 and uniting posteriorly about 390/a from posterior end of body. 

 Testes 18 to 20 in number, arranged in two irregular rows originating 

 anteriorly about 540/x, to 550/j, caudad of acetabulum and extending 

 slightly posterior to equator of body. Seminal vesicle small and 

 situated about midway between acetabulum and anterior testis. 



Female 3.7 mm. long by 100/x wide. Cuticle smooth. Oral sucker 

 poorly developed, 30/a in diameter. Ovary slender, loosely spiral, 

 390/x long when measured in a straight line and disregarding total 

 length of spiral, and slightly pre-equatorial in position. The vitel- 

 laria consist of transversely elongated follicles, and extend from the 

 distal pole of the ovary to the posterior end of body. Uterus long 

 and apparently containing but one Qgg. 



Cercaria unknown or unrecognized. 



Hosts. — Primary, birds {Marila affinis) ; secondary, unknown. 



Location . — Mesenteric veins. 



Distribution. — North America (United States; Shadyside, Md.). 



