72 G. A. MacCaArrum, 
The genital cloaca is bowl-shaped, the orifice being directed 
rather backward. It is lined by many fine sharply pointed spines 
direeted inward and upward and numbering at least eighty: behind 
these there are two small groups of similar spines. The vas deferens- 
and the uterus may be traced into this bowl-shaped opening. The 
vagina is very plainly seen as a single median tube leading from 
a dorsal opening to divide into the two lateral ducts of the vitel- 
larium which then reunite posteriorly to form the vitellarium reser- 
voir. The ovary is very indistinetly outlined. The eggs are thick- 
walled and deep yellow. They have only very short spur-like pro- 
cesses at each end with no filament, or are rounded at the ends. 
There are eight or ten rather large testes. The vas deferens 
terminates in a rather pyramidal or conical mass in the interior of 
the eloaca which is bordered by the two small accessory clusters 
of spines and may represent the cirrus. 
Measurements. 
Length 3 mm 
Width 0,6 
Sucker disc 1,0 xX.0,5 
Suckers 33 —45 
Testes 8—10 
Eggs 0,15 mm in length 
No filament 
Diam. of sucker disc 0,80 x. 0,60 
New York Fish Markets. 
M. poronoti n. sp. 
The are found pretty regularly moderate numbers of this species 
elinging to the gills of the Butterfish (Poronotus triacanthus) which 
were brought to the U. S. Fish Commission Laboratories at. 
Woods Hole. | 
The worm when at rest is about 6 mm long by 1 mm at its: 
widest part. There is a long caudal sucker disc armed with one 
hundred and twenty suckers which forms about one-third of the 
whole length of the worm. The suckers are flattened laterally: 
their chitinous skeleton is in general like that of M. centropristis 
but its lateral spur is very short. In one specimen they are seen 
from the edge and it is plain that the ends of the main arches are: 
