12 



Earle C. Stevenson 



laterally, and the pulp-filled cavity of the hook conforms to the 

 oval shape of the body as is shown in cross-section (pi. VI, fig. 

 50). The number of hooks on each individual head varies in both 

 species. The specimens under my observation gave a numerical 

 range of 34 to 48 for T. serrata, and of 30 to 32 for T. serialis; 

 the number of small hooks equaled the number of large hooks on 

 each head. 



The following table gives the observations of several authors 

 regarding the number and size of the hooks of the two species 

 under discussion : 



Taenia serrata 



Baillet (1866) 



Baillet (Deffke, 1891) 



Blanchard R. (1885) 



Deffke (1891) 



Dujardin (1815) 



Krabbe(1866) 



Kiichenmeister (1852) 



Kiichenmeister (Deffke, 1891) 

 1 Leuckart (Deffke, 1891) . . . . 



JLeuckart (1879) 



Railliet(1886) 



Railliet(1893) 



2 Stevenson (1904) 



Ziirn (1882) 



NO. OF HOOKS 



41-46 



34-36 



34-48 



34-38 



48 



40-42 



42 



34-40 



40-48 



38-48 



34-48 



34-48 



34-48 



38-42 



LARGE HOOKS: 

 LENGTH IN U 



135 



225-256 

 230-260 

 225-250 

 260 



'? erroneous) 

 230-240 

 276 

 230 

 250 



225-250 

 225-250 

 246-294 

 220-230 



SMALL HOOKS 

 LENGTH IN U. 



135-162 

 140-160 

 130-162 

 120 



130' ' ' ' 

 191 

 150 

 140 



i.36!i62 

 120-160 

 132-177 

 140-150 



1 I did not succeed in finding Leuckart's original figures quoted by Deffke 

 (1901), but the number of hooks given by Leuckart (1879), does not agree 

 with Deffke's citation. 



2 The present paper. 



202 



