14 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



TOU 6B. 



of large hooks. This alternating arrangement of the large hooks 

 is also observed in a lateral view of the head (fig. 8). The large 

 hooks are 320 to 365 [j. long. When the head is viewed from the front, 

 showing the dorsal edge of the hooks, the large hooks are an elongate 

 spindle shape, with a slight constriction along the middle portion. 

 The blade and the handle attain their maximum thickness of 27 [>. 

 at their middle points, diminishing to 20 [i, near the guard. From 

 the lateral view (fig. 9) the large hooks present a blade wdth a 

 moderate curve; a handle which is very variable in outline; it may 

 be continuous dorsally with the straight line of the 

 blade, and be almost straight, with a very slight 

 undulation and a small enlargement at the end, 

 this end tending to bend slightly in the ventral 

 direction, or it may narrow to a rather acute tip 

 and have a smooth or Imobbed outline; and a 

 guard that is somewhat triangular in outline or in 

 some cases with the proximal portion presenting almost parallel sides 

 and terminating distally in a triangular portion. The small hooks 

 are 180 to 200 [x long. Froni the lateral view they present a blade of 

 moderate curve ; a thick, short handle curving dorsally ; and a thick 

 irregularly triangular guard. The suckers are not prominent and 

 are 290 to 350 [>. in diameter. The neck is somewhat smaller than the 

 head and is 600 [i to 1.3 mm. long, measuring from the posterior 

 margin of the suckers to the first trace of segmentation. The strobila 



Fig. 8.— Taenia macro- 

 cYSTis. Lateral view 

 OFHEAD. X 42. After 

 LOhe, 1910. 



(fig. 10) attains a length of 12 cm., a 

 maximum width of 2 mm., and is com- 

 posed of 90 to 100 segments. The genital 

 pore lies near the middle of the segment 

 and is very prominent. The dorsal ex- 

 cretory canal lies lateral of the plane of 

 the ventral canal. The ventral canal is in 

 the ventral portion of the segment and not 

 merely ventral of the dorsal canal. The 

 transverse canal connects the two ventral 

 canals in the usual way. Youngest seg- 

 ments about 750 \l wide. About the eight- 

 ieth segment, the maximum width occurs, segments being 2.2 mm. 

 wide and 2.5 mm. long. The largest segments are 7 mm. long and 

 1.5 mm. wide. The genital primordia are visible about 1.5 mm. 

 back of the head in the median portion of about the twentieth seg- 

 ment. The cirrus pouch and vagina lie between the dorsal and 

 ventral excretory vessel and the longitudinal nerve is ventral of 

 the cirrus pouch and vagina. The calcareous corpuscles are 19 by 

 13 \i. in diameter. 



Male genitalia. — The testes are comparatively few in number and 

 are oval, the long axis paralleling the transverse axis of the strobila ; 



Fig. 9.— Taenia macbocystis 

 Large and small hooks. 



