504 Mr. H. A. Baylis on 
fifty stout bundles dorsally and a similar number ventrally. 
‘There is no very clear distinction into outer and inner layers. 
The genital ducts pass between the dorsal and ventral excre- 
tory vessels and ventrally to the longitudinal nerves. 
This form differs from J’. erostris (L6unberg), which occurs 
in the same host, in the larger size of the scolex, the slight 
development of the auricular appendages, the larger number 
of testes, and other details. 
Mesacestoidide. 
Mesocestvides litteratus (Batsch). 
Host : Vulpes vulpes (ved fox). Yukanski, 23. vil. 1917. 
This species occurred in considerable numbers in the upper 
part of the small intestine. 
Davaineide. 
Davuinea tetragona (Molin), var. lagopodis (var. n.). 
Host: Layopus mutus (ptarmigan). Murmansk, Kola 
Enlet,.2: vi, LOL. 
Two specimens of a Davainea closely resembling D. tetra- 
gona (Molin) were found ina ptarmigan killed at Kola Inlet. 
This species is stated by Clere* to oceur in Lagopus albus T 
in the Ural, but the present examples show certain pecu- 
liarities that seem to indicate a distinct variety. 
The length of a complete specimen is about 20 cm. and 
the maximum width 5mm. ‘The scolex measures 0°3 mm. 
across. ‘The suckers are oval, their longest diameter (antero- 
postelior) being about 0°14 mm. The diameter of the 
rostellum is 0°055 mm. It is armed with a single row of 
minute hooks, 8 wlong. The suckers are armed with several 
rows of very small hooklets. 
There is a considerable unsegmented neck, as in the typical 
D. tetragona. The segments are much broader than long, 
except the gravid ones near the posterior end. The trans. 
verse excretory vessels are very wide, often appearing as 
wide as the medullary portion of the segments between them. 
The genital pores are unilateral ; the cirrus-sac is small 
(0°15 mm. long), but muscular. The vas deferens is con- 
siderably coiled, but, as a whole, pursues a fairly straight 
* Bull. Soe. Oural. Sci. nat. xxx. 1910, p. 125. 
+ The bird referred to as ZL, albus seems more likely to have been 
L. mutus. The former, as | am informed by Mr. C. Chubb, is an 
American form, though it ranges into Scandinavia and Northern "Russia. 
