DESCRIPTION or I'LATES. XXI 



FIG-. 



4. Enlarged view of the spirally folded caudal extremity of the male Tricliocc- 



phalus. 



5. Part of the same, more highly magnified, to show, a, protrusor muscle ; b, cloacal 



aperture; c, slieath of the penis or appendix copulatorius (x 110 diam.). 



6. Exserted membranous vulva, showing the vaginal passage and retroverted 



spines (x 140 diam.). 



7. Four unimpregnated ova (x 220 diam.). 



8. Eully developed egg with a hisegmented yelk and highly refracting nuclei 



(x 180 diam.). 



These figures are original. — T. S. C. 



PLATE VI. 



1. Head of a male specimen of ProstJiecosaeter convolutus (magnified 60 diam.), 



which measured fifteen lines in length. From the lungs of the common 

 porpoise. The oesophagus and upper part of the intestinal tube are seen 

 through the integument. 



2. Caudal extremity of the same worm, showing the intromittent organ and 



accessory appendages. Viewed from behind (x about 60 diam.). 



3. A more highly magnified representation of the tail of the male seen from the so- 



called ventral aspect. It exhibits the great lateral raembranous appendages 

 in their fully expanded condition, a small pair succeeding them, the terminal 

 lobes surrounding (with their contained muscular organs) the cloacal 

 orifice, the sheath of the penis, the double intromittent organ, and the lower 

 part of the alimentary canal (x 220 diam.). 



4. Prostliecosacter convolutus. Female. Natural size. 



These figures are from drawings by Mr. Busk. 



PLATE VII. 



1. Anterior extremity of a female example of Prostliecosacter convolutus (magni- 



fied 60 diam.). 



2. Caudal extremity of the same, showing numerous embryos in the interior 



(x 60 diam.). 



3. Another view of part of the same, showing the prominent lateral vesicle, the 



uterine ca,nal, and a young embryo in the act of escaping per vaginam 

 (X 220 diam.). 



4. Section of the u.terus, with contained ova in various stages of development 



(X 220 diam.). 



5. One ofthe free embryos isolated (x 360 diam.). 



These figures are from drawings by Mr. Busk. 



PLATE VIII. 



] . Section ofthe intestinal tube of the speckled salamander (Lissotriton punctatus), 

 laid open to exhibit the mode of attachment of Echinorhynchus antlwria to 

 the mucous surface. Natural size. 



