eo PROCEEDINGS OF THE NATIONAL MUSEUM. 107 
a. 
0.08 millimeter, breadth 0.4 millimeter. In this specimen the first seg- 
- ments began about three millimeters back of the head. 
Some specimens with ripe segments contained ova which were 0.025 
to 0.03 millimeter in diameter, and which inclosed typical six-hooked 
embryos. ; 
Teenia macrocantha sp. nov. 
(Pl. vu, Figs. 79-82.) 
. 
Head subglobose, somewhat pyramidal; bothriain lateral pairs and 
little prominent; proboscis subeylindrical, expanded at apex, con- 
tracted at base; hooks ina single circle, large, nine (?) to thirteen ; body 
subeylindrical, segments very short and crowded together anteriorly, 
lengthening and narrowing posteriorly ; strobile, in aleoholic specimens, 
slightly arcuate with crenate margins; reproductive apertures margi- 
nal, allon one margin; cirrus long, filiform, and armed with exceedingly 
minute spines; largest specimen 15 millimeters long and 1 millimeter 
broad. 
HABITAT: Gdemia americana, Yellowstone Lake, Wyoming, August, 
1890. 
Following are detailed measurements of the largest specimen in the 
lot, dimensions given in millimeters: Length 15, diameter of head 0.75, 
diameter of neck 0.60, length of head 0.50, length of proboscis 0.42, 
diameter of proboscis at base 0.10, diameter of proboscis at apex ex- 
elusive of hooks 0.22, diameter of crown of hooks 0.35, length of hooks 
0.21, length of first distinct segment 0.025, breadth of first segment 
0.65, length of last segment 0.28, breadth of last segment 0.50, greatest 
diameter of body 1, diameter of cirrus 0.015 to 0.019, length of spines 
on cirrus not exceding 0.001. 
The number of hooks in this specimen was made out to be nine. In 
order to ascertain the number of hooks accurately, a specimen in which 
the proboscis was retracted, and which had presumably not lost any of 
the hooks after it had been put in alcohol, was taken and the set of 
hooks carefully dissected out. The number in this case was found to 
be exactly thirteen, and they were 0.22 millimeter in length. 
The hooks, when isolated, are seen to be of two sorts, as shown in 
Fig. 80. In the set of hooks examined, nine of the thirteen were like 
Fig. 80, a, the other four being like those of Fig. 80, b. This difference 
would probably be overlooked except where the hooks are isolated. 
The hooks resemble those of 7. megacantha Rudolphi, as figured by 
Krabbe (Bitrag til Kunds. om Fugl. Beend., 80, Pl. 1x, Fig. 251). There 
are, moreover, no characters which are absolutely contradicted in the 
published descriptions of that species. The descriptions of 7. mega- 
cantha are, however, deficient in detail, and since the hosts are widely 
different, T. megacantha being a parasite of species of Caprimulgus and 
Nyctibius, it has appeared to me best to refer my specimens to a new 
species. 
ie . 
