Prof. H. Karsten on Rhynchoprion penetrans. 311 



different parts, whilst the long moveable terminal joint of each 

 half of the labium in Rhynchoprion is not chitinous, and exhibits 

 no division into joints. 



EXPLANATION OF THE PLATES. 



(The magnifying power is indicated near the number of each figure.) 

 Plate VIII. 



Fig. 1. A posterior leg and a portion of the tail of a Field-mouse, with 



several imbedded individuals of Rhynchoprion, brought by 



Schmarda from Peru. 

 Fig. 2. An antenna. 

 Fig. 3. A female animal before its parasitism : at u the entrance into the 



fecundation-sac is shown, and under the large wing-like organ 



the smaller lateral plate pierced by a stigma. 

 Fig. 4. A female after it has been imbedded in the skin for some days. 

 Fig. 5. A mature egg from the ovary, under the same power as the female 



in fig. 3 : m, the micropyle. 

 Fig. 6. One of the large stigmata of the posterior dorsal half-segments of 



the female, with the neighbouring tracheal terminations. 

 Fig. 7. A stigma of the male, with a short trachea ; magnifying power 



the same as for fig. 6. 

 Fig. 8. Head of the female (fig. 4), seen in front. 

 Fig. 9. A female that has attained its full development in the skin, seen in 



front. 

 Fig. 10. Spermatophora. 



Fig. 11. The spermatozoids evolved therefrom, both taken out of 

 Fig. 12. The seminal receptacle, the efferent duct of which opens into the 



fecundation-sac (b), which is prolonged, on the one hand, into 



the efferent canal (a) of the ovary, and on the other into the 



vagina (v), with its mouth («). 

 Fig. 13. A portion of a greatly thickened trachea of the parasitic female. 

 Fig. 14. Another greatly thickened tracheal branch, of which the inner 



originally spiral portion, which is now uniformly thickened, lies 



in the tenacious internal enveloping membrane. 



Plate IX. 



Fig. 1. A male Rhynchoprion; the internal chitinous parts of the sexual 



apparatus indicated as shining through. 

 Fig. 2. The abdomen of an individual in which the sexual organs were 



protruded. 

 Fig. 3. A maxilla (nix), with the maxillary palpi (t), the mandible (md), 



the labium (l), and the mentum (k), drawn from the inside. 

 Fig. 4. The same, from the outside. 

 Fig. 5. The external parts of the sexual apparatus, seen from beneath, 



after the individual parts had been somewhat separated by a 



gentle pressure. 

 Fig. 6. The same parts, with the organs situated within the abdominal 



cavity, seen from the side (see p. 309). 

 Fig. 7. The labium, seen from beneath. 

 Fig. 8. Its lower part, seen from above. 

 Fig. 9. A male animal, seen from above. 



