DrAcram illustrating my hypothesis of the relations of the several 
forms and stages of Cestode larvee described in Herdman’s 
Report. 
(The letters correspond to those in the above diagrams. 
Those 
marked A’, A”, B’, and J' are regarded as parallel stages to 
A, B, and J.) 
Species I. Tetrarhynchus unionifactor. 
7X 
oo, (?) swallowed by 
Pearl-Oyster ; hatch- 
ing out in intestine to 
\ 
\ 
\ 
\ 
x 
Eoo 
become 
— > 
F 
D 
Larval Tetrarhyn- 
chus unionifactor, in 
and around the ali- 
mentary canal of the 
Pearl-Oyster. 

¥ 
Adult Tetra rhynchus 
unionifactor 
mentary canal of Rhi- 
noptera javanica and 
Ginglymostoma 
color. 
in ali- 
con- 
Species II. Tylocephalum ludificans. 
B 
(?) 
Hornell’s free- 
swimming 
larva. 
vA 
wee 
La 
A M 
px A q Cc 
ee Se . 
Egg, (?) hatching in~ Se Globular cysts, T'ylo- 
sea-water to become B cephalum  ludificans, 
or (?) swallowed by = in liver and connective 
Pearl-Oyster to be- tissues of the Pearl- 
come C, NY Oyster. 
\ 
x ¥ 
J 
An adult Tyloce- 
phalum-like form in 
one of the oyster-eat- 
ing Elasmobranchs; 
probably  Aétobatis 
narinari. 
Proc. Zoou. Soc.—1912, No. XIX. 19 
[31] 
