8 H. B. FANTHAM. 
in the gut are somewhat thinner than those normally occur- 
ring in the crystalline style. . 
In the case of Spirocheta anodonte the infected 
mussels nearly always contained crystalline styles, in which 
the parasites could be descried actively swimming. About 
80 per cent. of the mussels were infected. 
The position and connection of the crystalline style of 
Anodon have been well described by Mitra (28), except that 
his figure of the natural size of the style is quite wrong. 
This structure is usually 5 cm. to 7 cm. in length, and 0-5 em. 
to 0°7 cm. broad; at any rate those are the dimensions I 
found after careful measurement of numerous specimens. It 
is irregular at the anterior end, but tapering at the posterior 
one. It is not definitely joined up to the cuticular lining 
(“‘fléche tricuspide”’) of the stomach, but a granular loose 
coagulum often connects them. ‘This structure is discussed 
more fully in Appendix I, and is only mentioned here in con- 
nection with the occurrence of the parasites therein. I have 
sometimes found 8. anodonte in the “ fléche tricuspide ” 
of Anodons from Godalming, but the Spirochete always 
occurred in the crystalline style. I never found 8. balbianii 
in the “ fléche tricuspide” of Ostrea, whether the oyster 
was infected or not, and Perrin mentions that he never found 
it there; at least, I think that it is the ‘ fléche tricuspide” 
that he really means when he remarks: “In the anterior 
part of the stomach is another structure, the meaning of 
which I am unable to explain. This structure is connected 
with the anterior end of the style by a dark-coloured mass of 
diatoms. It is an irregular mass conforming to the shape of 
the anterior region of the stomach, is transparent and crystal- 
line, and of a firmer consistency than the style itself. It is 
very regular in its occurrence, and after prolonged periods 
of starvation still appears to retain its place. It contains no 
Trypanosomes” (9, p. 134). 
The Spirocheetes swim about most actively in the colloidal 
substance of the style in all directions and planes, often 
suddenly reversing their path of motion. 
