DR. T. $. COBBOLD ON ENTOZOA. 169 
TREMATODA. 
Fasciola gigantica, 7. S. C. Distoma clavigerum, R. 
hepatica, Linn. ——- cylindraceum, Zed. 
Campula oblonga, 7. S. C. —— fulvum, R. 
Hemistomum spathula, Dies. —— gracilescens, R. 
Echinostomum spinulosum, R. |o —— hispidum, Abildg. 
Monostoma caryophyllinum ?, Zed. —— rachion, T. S. C. 
dubium, T. S. C. Polystoma integerrimum, R. 
Distoma atomon, A. 
The names here abbreviated are those of Rudolphi, Bremser, Dujardin, Diesing, Linneus, Zeder, 
Creplin, Frölich, and Abildgaard. 
NR WO tO 
c9 
. 10. One of the above, enlarged 40 diameters. It exhibits the regularly arranged dermal spines 
ll. 
> 12. 
«13, 
. 14. 
. 15. 
. 16. 
17; 
DESCRIPTION OF THE PLATES. 
Tap. XXXI. 
. Tænia filicollis. Natural size. 
. Monostoma caryophyllinum, imperfectly developed. Natural size. , 
. The same, showing an oral sucker and cells in the interior. Magnified 300 diameters. 
. Monostoma dubium (mihi). Natural size. 
. The same, displaying the elongated ventral appendage and internal gastric cæca. Enlarged 200 
diameters. 
. Four examples of Distoma fulvum. Natural size. 
. One of the above, showing the position of the suckers and the extremely attenuated neck during 
elongation. Enlarged 20 diameters. 
. The same, during contraction ; it also exhibits the intromittent organ and ova within the uterine 
tube. Magnified 60 diameters. 
Three specimens of Distoma rachion (mihi). Natural size. 
investing the whole of the body; an oral and ventral sucker, the lining membrane of the former 
consisting of polygonal cells; a narrow æsophagus communicating with a broad, elongated, 
horse-shoe-shaped digestive cavity—in front of the latter a wide uterine tube symmetrically 
disposed in coils on either side and filled with ova; and an internal seminal vesicle. The ovary 
is placed immediately above the caudal vesicle, and is surmounted by the testes. 
Transparent cyst from the subperitoneal surface of the intestine of a Haddock. Natural size. 
The same, ruptured. Magnified 4 diameters. 
Scolex of Tetrarhynchus, escaped from the cyst. 
large caudal vesicle, the surface of which is slightly segmented an 
sclerous particles. Magnified 4 diameters. 
The same with the body and proboscides evolved. Natural size. ; hylloid 
Part of the Scolex, enlarged 20 diameters. It exhibits the four narrow and pointed phylloi 
bothria, a portion of the transparent caudal vesicle with its sclerous particles, and more particu- 
larly the four proboscides, two of which are partially withdrawn from their sheaths. 
An oval sclerous particle, magnified 200 diameters. 
Section of a proboscis or tentacle, showing the pecul 
Magnified 200 diameters. 
It shows the head and body enveloped by the 
d dotted by the highly refracting 
jar arrangement of the hooks and hooklets. 
