484 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [32] 
applied to their heads. This was characteristic of those of the first lot. 
With those found in the spiral valve, however, the case was quite 
different. In it these parasites were found to be firmly attached to the 
wall of the intestine. Many of them had tunneled holes in the mucous 
and submucous coats. In some cases these tunnels cut through the 
muscular coats of the intestine and opened into the interior body cavity. 
In some instances several heads were found occupying the same cavity. 
One of these pockets was 6.5™™ deep. Init were imbedded three heads 
belonging to three strobiles 20™", 32™™, and 55™™ Jong, respectively. 
The heads were so tightly fastened in their fleshy cavern that they had 
to be cut out before they could be removed. <A peculiarity of the in- 
dividuals of this second lot is a tendency to contract the anterior seg- 
ments, so that instead of being attenuated as in most of those of the 
first lot, the anterior segments are at first nearly as broad as the neck, 
and immediately widen until they are as broad or even broader than 
the head. This gives the worm the appearance of being constricted 
just back of the head. This habit of tunneling into the flesh of its host 
must make this parasite a very unpleasant guest. Usually in the case 
of those Cestoidea which infest the alimentary canal of their host, their 
presence cannot give rise to much pain, unless they are present in 
numbers sufficient to occasion obstruction. But with this worm it is 
quite otherwise. Wherever tunnels in the walls of the intestine caused 
by this worm were observed, it was noticed that there was much irrita- 
tion of the mucous membrane. Not only was the mucous coat highly 
inflamed, but the inflammation often extended into the submucous and 
muscular coats. The whole interior of the spiral valve was blotched 
with angry-looking sores. If this is at all common, then we find in 
this worm an enemy of the Dusky Shark, small but not insignificant. 
It is certainly encouraging to find in nature, in the too small army of 
enemies which are arrayed in warfare against the Selachians, these 
humble sappers and miners lending their aid towards keeping down the 
numbers of these Ishmaelites of the sea. 
Abnormal forms.—In the second lot a few monstrosities were ob- 
served, two of which are figured (Plate IV, Figs. 21 and 22). The 
first example, Fig. 22, is a strobile 13™™ in length, which, at about 2™™ 
from the posterior end,. gives off from the postero-marginal edge a sec- 
ondary strobile, in which there are about four joints faintly marked. 
The dimensions of the segment which sends off this budding part are: 
Length, 0.1™; breadth, 0.72™™; of the succeeding segment, length, 
0.1™™; breadth, 0.62"; of the budding portion, length, 1.08"; breadth, | 
0.06", The second example, Fig. 21, is a fragment; length of strobile 
not known. The segments have the beginnings of the male genital 
organs. A secondary strobile is given off from the margin of the pri- 
mary strobile in a somewhat different manner from the one just de- 
scribed. A tendency towards a marginal thickening can be seen on the 
third segment in front of the one from which the secondary strobile 
becomes free. In the succeeding segments this marginal thickening, 
