DIBOTHRIA FROM YELLOWSTONE NATIONAL PARK. 
79 
EXPLANATION OF PLATE XXVII. 
Fig. 1. Cyst contaiiiiug embryo from iiyloric ciBca of Salmo mylciss. X 0. 
Figs. 2, 3, 4. Embryos liberated from tlioir cysts. X 15. 
F'g. 5. Lougitiulinal section of longitndinal vessels of specimen from abdominal walls of host; sections 
from same region of body as that of Fig. 4, PI. IV. X about 300. 
aa. Spaces where aquiferous vessel is cut through ; the essel is seen to have both longitudinal 
and circular muscle libers in its walls. 
h. Lnmen of marginal canal ; the spongy tissue which tills it has a striated appearance in longi- 
tudinal section. 
c. Nuclei. 
(Id. Calcareous bodies. 
Fig. C. Part of transverse section of embryo from cyst in pyloric creca, highly magnified. 
a. Epidermis. 
a'. Cuticle. 
1). External layer of longitudinal muscles. 
0 . Nuclei. 
d. Inner layer of longitudinal muscles. 
e. Parenchyma, with connective tissue fibers and nuclei. 
/. Peripheral aquiferous vessels. 
g. Central aquiferous vessel. 
h. Marginal canal. 
it. Calcareous bodies. 
fc. Nuclei surrounding marginal vessel. 
Drawings by the author. 
