S. Yoshida 
5H3 
Specimens resembling the above were collected 29. v. 1907, from 
Cynias manazo in Tokyo. Though much narrower they were nearly 
as long as specimens obtained in Hiroshima; the head is smaller, the 
border of the bothridia thinner and more loosely folded; the strobila 
is smooth, without rupture or groove. 
2. Crossobothrium angustum (Linton, 1889). 
(Plate XXIII, figs. 1—5.) 
Syn. Orygmatobothrium angustum Linton, 1889. 
The material at my disposal was collected by Mr T. Tsuchida from 
the spiral valve of Triakis scyllium Muller and Henle, at Misaki ll.^viii. 
1906. The characters of this worm agree well in most respects with 
those of Linton^s species and it is reasonable to suppose that they are 
identical. Linton’s statements, made on the several occasions, are 
based chiefly upon the external characters and not on the internal 
structures. Therefore, my description which follows is more complete 
as it includes also a consideration of the internal structures. 
External features. The worm measures 10—30 mm. in length ; 
most specimens attain a length of 25—30 mm. In large specimens 
the widest posterior segment measures 1*1 mm. in breadth, whilst the 
narrowest portion at the neck measures 0-1 mm. in breadth. The head 
(PI. VII, fig. 1) is generally pyramidal in shape and the size varies 
slightly according to the state of contraction of the bothridia, being 
on an average 0'6 mm. x 0*6 mm. g,t the posterior widest portion'.' 
There are four bothridia, unarmed and elongated oval in shape when 
at rest; anteriorly narrowed, somewhat roundly pointed, surmounted 
at the apex by a supplemental disk or accessory sucker (axiliary 
acetabulum); posteriorly rounded, broader than anteriorly, and flaring 
away from the neck so as to turn its surface outward. The margin of 
the bothridium is entire and is more or less thickened. The bothridium 
is 0-57—0-6 nim. long and 0*3—0-35 mm. broad at the widest part 
near the posterior extremity. Linton observed in living, actively 
moving specimens, that the anterior end of the bothridia “ frequently 
elongated and curve outward and back in horn-like prolongation. An 
opposite movement is that in which the anterior ends of bothridia are 
closely oppressed and the broadly rounded posterior end are curved 
outward and forward.” Unfortunately I have not had any oppor¬ 
tunity to observe hving specimens, and in my alcoholic specimens 
I do not find the prolongation of the anterior ends of bothridia. The 
Parasitology ix. 37 
