T^NIOID CESTODES OF NORTH AMERICAN BIRDS. 47 



In general structure the form from Fulica americana and Jacobi's 

 species are alike, and the cirrus pouch and cirrus in size and shape 

 are practically the same in both. Comparing, however, the length 

 of the hooks of Jacobi's species, 23/x, with that of the hooks of the 

 form which I have described, 38/a, and taking into consideration the 

 lack of a seminal vesicle in the former, its presence in the latter, the 

 small size of the fully developed ovary in the former, and the very 

 large size of the ovary in the latter, it seems necessary to look u]3on 

 these forms as two ditferent species. 



Diorchis acuminata^ collected from Anas crecca, A. stre/pera^ and 

 Fulica atra, as described by Clerc (1903, pp. 281-284, pi. 8, fig. 13; 

 pi. 9, fig. 25; pi, 11, figs. 78, 88), measures about 80 mm, in length 

 and 1.2 mm. in maximum breadth. The width of the head varies 

 from 230 to 320/^,. The rostellum is armed w^ith 10 hooks 27 to 

 39ju, in length. The segments are broader than long throughout the 

 strobila, the usual ratio being 14 to 1. Fully developed eggs are 

 present in segTiients 50 to 60 mm. from the scolex, and the female 

 genital glands are well developed in segments 25 mm. from the scolex. 

 The genital pores are unilateral. The excretory vessels are without 

 commissures in the posterior part of the segment. The longitudinal 

 muscles are arranged in two layers, numerous small bundles in the 

 outer layer, and 8 larger bundles in the inner layer. The vagina and 

 cirrus pouch pass dorsal of the excretory vessels and nerve. There 

 are two testicles present in each segment, reaching their maximum 

 development in segments 15 to 17 mm. from the head. The cirrus 

 pouch measures at its maximum of development 150 to IGO^u, in length, 

 is straight or slightly curved, shaped like a thick spindle, and does not 

 reach the median line of the segment. Its musculature consists 

 especially of longitudinal fibers. The female glands occupy very 

 little space, never exceeding in size one-third of the Avidth of the 

 segment. They are located exactly in the middle of the segment 

 beneath the testicles. The ovary is "double, non lobe, en forme 

 d'haltere recourbe dont les extremites epaissies sont tournees vers la 

 face dorsale." The yolk gland is globular, small, and located between 

 the two wings of the ovary. The vagina is ventral of the cirrus 

 pouch. Its initial portion is muscular, the remainder is swollen, 

 possesses thin walls and acts as a seminal receptacle. The uterus is 

 sac-like. At the beginning of its development it is like a narrow 

 transverse canal. It develops large lobes which penetrate between 

 the longitudinal muscles and beyond the excretory vessels. The eggs 

 are elongated in form. 



The only differences between the form from Fulica americana and 

 Clerc's species, so far as may be determined from Clerc's description, 

 are in the length of the cirrus pouch (which is slightly greater in the 

 specimens from Fulica americana) and in the shape and size of the 



