54 



ILLINOIS BIOLOGICAL MONOGRAPHS 



[54 



1900: 

 1911: 



PROTEOCEPHALUS EXIGUUS La Rue 



[Figs. 14, 50-52, 118, 135-138] 



Proteocephalus filicollis Benedict, 1900:355-365 

 Proteocephalus exiguus La Rue, 1911 :477-478 



Specific Diagnosis: Characters of genus. Strobila short and 

 slender. Length 9-15-25-38 mm. Maximum breadth 0.425-0.646-0.8 

 mm. Segmentation not evident. Intersegmental furrows shallow. 

 Neck 2-4-7-10 (?) mm. long by 0.10-0.20 mm. broad. First proglottids 

 longer than broad or nearly quadrate. Mature and ripe proglottids 

 longer than broad. Ripe proglottids considerably larger than mature 

 ones, 0.680-1.190 mm. long by 0.460-0.595 mm. broad. End-proglottid 

 elongated, pointed posteriorly, 0.714-1.50 mm. long by 0.40-0.646 mm. 

 broad. Head somewhat globular, flattened dorsoventrally, bearing four 

 suckers on its broadest part. Breadth of head 0.120-0.160-0.170 mm. 

 Suckers 0.058 mm. broad by 0.069-0.085 mm. long. Opening of suckers 

 about 0.040 mm. in diameter. Fifth sucker muscular, functional, 0.037- 

 0.048 mm. in diameter. Common genital sinus alternating irregularly, 

 situated near middle of lateral margin of proglottid. Testes 35-54 in 

 number, in one layer, between vitellaria, anterior to ovary. Diameter 

 of testes 0.04-0.05 mm. Vas deferens forming mass of coils in mid-field. 

 Cirrus-pouch 0.289-0.340 mm. long, reaching to the middle of segment. 

 Cirrus straight, 0.10 mm. long when protruded. Vagina anterior to 

 cirrus-pouch, crossing cirrus-pouch near middle. Sphincter vaginae 

 weak, 0.008 mm. thick. Lobes of ovary retort-shaped with smooth out- 

 lines. Vitelline follicles small, not compact. Uterus when fully devel- 

 oped with 9-14 lateral pouches on either side. Embryos about 0.019- 

 0.021 mm. in diameter, second egg membrane 0.036-0.046 mm., outer 

 membrane 0.038-0.06 mm. 



Habitat: In stomach (probably by post-mortem wandering) and 

 intestine of host. 



Type : Alcoholics No. Ch. 7c, Ch. 2c, and an unnumbered bottle in 

 Doctor H. B. Ward's collection, from Coregonus nigripinnis, C. progna- 

 thus, and C. artedi. Type locality, Lake Michigan, near Charlevoix. 



