578 



Eggs with thin transparent 

 shells: frequently in egg 

 capsules, in some cases 

 scattered through the 

 segment; head nearly al- 

 ways armed with hook- 

 lets on i-ostellum: larvil 

 stage a oysticercoid: 

 adxilts in birds and mam- 

 mals 



(Suckers unarmed. 

 Suckers armed with min- 

 ^ ute hooklets (with four 

 I exceptions known only in 

 I birds). 



Jenital pores double 



;enital pores single, ir- 

 regularly alternate or un- 

 ilateral 



Two submedian ovaries in 

 each segment 



One median ovary In each 

 segment 



Several rows of hooks upon 

 rostellum 



.\ single row of hooks upon 

 rostellum, 



U.irsali root of hook much 

 longer than ventral rotit 

 or prong; ventral root 

 very short; hooks S to 12 

 rarely to 26) in number; 

 known only in birds 



Dorsal root of hooks about 

 the same length as ven- 

 tral root and prong, . . . 



Dorsal root shorter than 

 prong or ventral root; 

 hooks generally less than 

 •20 in number (range from 

 10 to 26); genital pores 

 unilateral or irregularly 

 alternate: known only in 

 birds 



D1PYLIDUN.\E. p. 5S5 



p. 5S6 

 .\M.\B1LIA, p. 5SS 



IMl'YLIDIUM, p. 5Stf 

 COTUONI.V, p. 5SG 



DRErAN 1 DOTA ICN 1 A. p. 



UIORANOTAENIA. 



.591 



lAs the terms anterior and posterior in referring to the roots 

 of the hooks are reversed b.v some authors. 1 suggest the use 

 of the woixJs doi-sal and ventral in their place. These words 

 are not open to misinterpi-etatlon, the dorsal root being a con- 

 tinuation of the dorsum of the prong; the ventral root lies 

 under the prong. 



