TiENIOID CESTODES OF NORTH AMERICAN BIRDS. 39 



is almost perfect correspondence in the characters of the strobila so 

 far as may be determined from Magalhaes's description. The struc- 

 ture which Magelhaes interprets as a seminal vesicle corresponds to 

 the seminal receptacle in my specimens. The eggs of the two forms 

 agree in size, number, arrangement, and in all respects except the size 

 of the hooks of the oncosphere, a difference which, on account of the 

 small size of these structures and the consequent liability of error in 

 measurement, can not be considered of great importance. 



The species which I have identified as Taenia cantaniana has been 

 found several times in this country in chickens and once in a pea- 

 fowl. After brief study it became evident that it belonged in the 

 genus Hymenolepis and not in Daoainea^ where it has been commonly 

 placed. The following description is based on specimens in the col- 

 lection of the Bureau of Animal Industry, Nos. 4109, 4198, 4569, 

 14554, and 14814 from chickens, Maryland and District of Columbia, 

 No. 14423 from a peafowl. District of Columbia, and No. 2761, col- 

 lected from a turkey in France by Railliet and determined by him 

 as Tcenia cantaniana. 



External anatomy. 



The specimens (fig. 28) which I have examined vary in length 

 from 2 to 12 mm. The maximum breadth is about 0.4 mm. The 

 head measures 120 to I6O/1, in width and thickness, by 100 to 120/a in 

 length. 



The rostellum is rudimentary, an elongated sac-like structure in 

 the central axis of the head, 80/x long by 35|ii in diameter, into the 

 anterior end of which is a deep, narrow invagination with cuticular 

 lining 30 to 40/x in de^jth by 4 to 6/i, in diameter. 



The suckers measure 60 to TO/x in diameter. In none of the speci- 

 mens studied, including some which were very young and immature, 

 was there any trace of hooks either upon the rostellum or suckers. 

 The neck is 80 to 90/^ wide by 100 to 130/. long. 



The width of the strobila gradually increases from the neck toward 

 the posterior end, near which it reaches the maximum. 



The segments are considerably broader than long throughout the 

 strobila, the posterior angles project but slightly, and there is no 

 overlapping of the posterior border of one segment over the anterior 

 portion of the next following segment. A strobila 6.5 mm. long 

 consisted of about 100 segments, of which the posterior 13 contained 

 fully developed eggs. In the widest portion of this strobila the 

 segments measured 80/. in length by 250/i in width. A strobila 8 mm. 

 in length consisted of about 215 segments, of which the posterior 

 16 contained fully developed eggs. In the widest portion of this 

 strobila the segments were 60 to 70/t long and 300/1 wide. Segments 



