ART. 7 CESTODE PAEASITES OF BIEDS LINTON 13 



TETRABOTHRIUS MACROCEPHALUS (Rudolphi) 



Figures 23-31 



Scolex. — There is a great variety of size and form; bothria oval- 

 elliptical; anterior appendage prominent in larger scoleces, less 

 prominent in smaller scoleces. 



Strobile. -T-T\\e larger strobiles are robust, thickish, neck sub- 

 cylindrical; proglottides begin a short distance back of scolex, at 

 first very short, increasing in length very slowly, much crowded, 

 very much broader than long; ripe proglottides ma}^ become half as 

 long as broad. Younger strobiles somewhat cylindrical, proglot- 

 tides at first crowded, much broader than long, becoming nearly as 

 long as broad. In all cases the margins of the strobiles are more or 

 less serrate. In some of the longer strobiles the adult and ripe 

 proglottides are somewhat campanulate. These are less robust than 

 the majority of the longer strobiles, the proglottides are less crowded 

 and of greater relative length. The scoleces in these two forms 

 agree in details of structure. The muscular genital cloaca is situ- 

 ated near the margin at about the middle of the length of the 

 proglottis. The cirrus opens on a small papilla, at the base of which 

 is the opening of the vagina. The cirrus-pouch is at the median 

 border of the genital cloaca. The cirrus is short and smooth; the 

 rather voluminous vas deferens lies on the dorsal side of the medul- 

 lary space, in some cases extending from the cirrus-pouch nearly 

 to the median line; in one case it was observed to surround the 

 dorsal excretory vessel. The exact number of testes is difficult to 

 determine. They are rather numerous, as many as 20 appearing 

 in the same transverse section, and representing from 35 to 40 or 

 more in the proglottis. In a whole mount the number of testes, in a 

 proglottis measuring 0.28 mm. in length and 0.56 in breadth, Avas 

 estimated to be about 40. The diameter of the cirrus-pouch is about 

 0.075 mm. The vagina lies on the ventral side of the cirrus-pouch, 

 is at first slender and more or less sinuous. It passes mediad near 

 the ventral excretory vessel, enlarges, and continues mediad on the 

 ventral side of the vas deferans to the border of the small, lobed 

 vitelline gland, where it turns abruptly ventrad. The vitelline gland 

 lies at the median line towards the anterior end of the proglottis, 

 in front of the lobed ovary. The uterus, in ripening proglottides, is 

 much lobed, the lobes tending to become obscure, or to disappear 

 entirely in the older proglottides, which are filled with ova. Diam- 

 eter of ova about 0.045 mm. The ventral excretory vessels are much 

 larger than the dorsal, oval in section, the dorso-ventral diameter 

 the greater, and, in a few series of sections, relatively large transverse 

 vessels were shown at the posterior ends of the proglottides connect- 

 ing the ventral vessels. In the scolex the vessels are abundantly 

 distributed in the axial region, and at the lateral margins between 



