572 
Cestodes from Selachians 
and appearing as mere transverse striation, but the segments gradually 
increase in length and breadth. The last widest segments measure 
T3—T5 X 0-5—0-6 mm. Thus the segments are broader than long 
throughout the whole length of the body; they number about 450. 
The genital openings are irregularly alternate. 
Genital organs. All my specimens are immature and there is no 
trace of the genital gland excepting the testes. The testes and the 
genital ducts appear in the posterior segments only and the latter 
are not as yet differentiated into the male and female ducts, being 
either mere cell masses or small canaliculated groups of cells. The 
testes scatter in the medullary portion of segment, being arranged 
in a single layer. In th^ anterior section of the segment, they occur 
in one row, 14 in number being traversed between two lateral excretory 
canals; in the posterior part of the segment, the transverse row of 
testes is separated into two lateral parts by the Anlagen of the genital 
ducts; on the porose side the row consists of 6—10 testes and on the 
aporose side 8—12. The testis is oval or spherical in shape, measuring 
0-03—0-04 mm. in diameter. The genital ducts are represented at 
this stage by undifferentiated masses of cells which pass between the 
dorsal and ventral excretory canals. 
Musculature. The longitudinal bundles of muscles are strongly 
developed, especially in the neck region where they are clearly visible 
from the exterior in total-preparations. The number of bundles 
increases in the posterior part of worm there being ca. 110 in all. The 
muscular bundle is largest along the median line of the segment both 
ventrally and dorsally, and decreases in size laterally. 
Excretory canals. There are four main canals as in other Cestodes; 
both the dorsal and ventral canals are nearly equal in width anteriorly, 
measuring 0-022—0-03 mm.; seen in cross section they are round but 
in the posterior region they become oblong in cross section ; the dorsal 
canal is much smaller (0-22 x 0-01 mm.) than the ventral (0-034 mm. x 
0-02 mm.). 
Affinities. From the above description it is clear that the worm 
most resembles A. coronatum (Rud.), therefore I provisionally identify 
it with this species, though there are some points of difference: (1) 
longer neck, (2) shorter posterior segments due probably to the immature 
state of my specimens, (3) larger size 
