24 PROCEEDINGS OF THE NATIONAL MUSEUM. tol. 55. 



outline when viewed from the side, and with a proximal protuberance 

 toward the side of the blade. The lines of the handle and guard do 

 not meet but are separated by a rather long interval, slightly to 

 strongly convex in outline when viewed from the side. The distances 

 from the distal extremity of the guard to the distal extremities of the 

 blade and handle are very nearly equal. Viewed from the front the head 

 (fig. 28) is approximately square with the suckers located at the corners 

 and separated by relatively wide intervals from one another. The 

 suckers are round to elliptical with a maximum diameter of 310 to 

 330 \t.. The neck is but slightly narrower than the head and is 680 \). 

 to 1.7 mm. long from the posterior margin of the suckers to the first 

 distinct segmentation. The strobila attains a length of 60 cm. to 2 

 meters, average specimens being 90 to 100 cm. long and consisting of 

 about 400 segments. The maximum width is about 4.8 mm. The first 

 segments are very short and much wider than long. There are some- 

 thing less than 175 of these preceding the mature segments. The 

 segments become mature and quadratic in shape about the hundred 

 and seventy-fifth. There are about 25 of these mature quadratic seg- 

 ments. They are about 4.9 mm. long and 4.2 mm. wide at the anterior 

 margin, 4.7 mm. wide at the posterior margin, and 4.8 mm. wide at 

 the genital pore. Complete maturity is attained in about the two- 

 hundredth segment, 25 cm. behind the head, and posterior of this the 

 segments transform into gravid segments. There are 30 to 40 gravid 

 terminal segments, making up almost half of the entire strobila, these 

 segments attaining a length of 1 cm. and a width of 4 mm. The pos- 

 terior angles of all segments are prominent, giving a characteristic 

 serrate appearance to the strobila. The calcareous corpuscles are 

 variable in shape and have a maximum diameter of 18 [x. The longi- 

 tudinal excretory canals are about 640 /x from the lateral margin of 

 the segment and 770 [jl from the genital pore. The transverse excre- 

 tory canal has the customary position in the posterior portion of the 

 segment and connects with the ventral canal. The genital pores are 

 irregularly alternate, commonly two in succession on one side and 

 rarely as many as four to six in succession. The genital papilla is 

 only moderately prominent and is located near the middle of the 

 segment except in gravid segments where it frequently is distinctly 

 posterior of the middle. The genital primordia are visible in toto 

 mounts in the fifth to the twelfth segments back of the head. 



31 ale genitalia.— The testes (fig. 31) are round or slightly elon- 

 gated in outline and are 132 by 96 jjl in diameter. There are about 

 400 to 500 in a segment, and they occupy nearly all the field included 

 between the longitudinal excretory canals not actually occupied by 

 other genital structures. In the posterior portion of the segment 

 they fill the lateral fields clear up to the median stem of the uterus, 

 leaving only little more than the width of the uterus free of testes 



