243] PROTEOCEPHALIDAE—LA RUE 243 



Ventral uterine openings 2-8 in number. Outer egg membrane ellip- 

 soidal, 0.026 by 0.037 mm. or sometimes spherical 0.032 mm. in diame- 

 ter; second egg membrane 0.021-0.023 mm. Embryos 0.015-0.016 mm. 

 Outer membrane smooth. 



Type : Specimens in collections of United States Bureau of Ani- 

 mal Industry, No. 14854. 



Habitat: In intestine of Ancisirodon piscivorous Holbr. (type 

 host), National Zoological Park. The locality from which this host 

 came is not known. The species is found only in North America. 



La Rue (1911:481) described this species in a preliminary way. 

 Six or eight heads together with numerous pieces in a bottle bearing the 

 U. S. Bureau of Animal Industry number 14854 were labelled "Ichthy- 

 otaenia: host Ancistrodon piscivorous; location, intestine; locality Nat. 

 Zoo. Park, collected S. S. Shawhan. Nov. 18, 1907." These were 

 secured for the writer's study by Professor Ward. 



No complete worm was found. The largest piece was 200 mm. 

 long and 3.5 mm. broad at the anterior end and 4.25 mm. broad at the 

 posterior end. This piece was made up of proglottids that were well 

 advanced in development, being nearly mature at the anterior end and 

 nearly ripe at the posterior end. The younger proglottids were not 

 distinctly separated by furrows but the more mature ones showed very 

 evident segmentation. Judging from the size of the segments and their 

 state of development it seems likely that the whole worm would attain 

 a length of 300-400 mm. or perhaps even more. Like other species of 

 Ophiotaenia the body is quite flattened. However, the body is thicker 

 than has been observed by the writer in O. cahnettei, O. nattereri, O. 

 trimeresuri, O. perspicua, and Crepidobothrium gerrardii. The head 

 (Fig. 38) is large tho not so large as in O. marenzelleri (Barrois) or 

 Crepidobothrium gerrardii (Baird). It measures 1.0-1.2 mm. in diame- 

 ter at the base of the suckers. The scolex, measured from its tip to the 

 base of the suckers has a length of 0.50-0.60 mm. There is no rostellum, 

 no hooks, no fifth sucker, and from toto mounts no vestigial fifth sucker 

 may be observed. As yet no sections of the head have been made. 



The four deep suckers are borne on the broadest part of the head 

 and these are directed outward. They are not prominent, are strongly 

 muscular, nearly circular in outline and they lack the upward pointing 

 projection that is always found in the suckers of C. gerrardii. The 

 suckers measure 0.34-0.35 mm. in transverse axis by 0.35-0.36 mm. 

 in longitudinal axis. The cavity of the sucker is deep. Its open- 

 ing measures 0.15-0.17 mm. in longitudinal diameter by 0.20-0.22 mm. 

 in transverse diameter. Immediately back of the head there is some- 



