12 C. S. MINOT ON DISTOMUM. 



Note. Since this article passed from my hands, three papers on the anatomy of Trem- 

 atods have appeared. The first is by Dr. Cobbold, 1 and does not contain anything of spec- 

 ial interest in connection with the views above advocated. Dr. Cobbold is apparently 

 unacquainted with the discovery of the vagina, and makes no mention of any structure 

 corresponding to Laurer's canal, which Huxley however describes, 2 in Aspidogaster conchi- 

 cola, as running from the upper end of the oviduct (i.e., the uterus) back to the testis. 

 He adds in a note that the description is based upon observations made before the publica- 

 tion of Blumberg and Stieda's discoveries, and at that time he had no doubt of the connec- 

 tion of the canal with the testis. The third and most important article is a capital memoir 

 by Dr. Wierzejski, 3 who describes in a Calicotyle from Raja Schulzii, a double vagina, so 

 that the female apparatus has three external openings, and resembles very closely that of 

 Polystomum as described by Zeller (I. c). 



Explanation of Plate I. 



The drawing on stone was made by Mr. J. H. Etnerton, to whose admirable skill I am much indebted. 



LETTERS COMMON TO ALL THE FIGURES. 



P.m. Basement membrane. Ov. Ovary. Sp.d. Spermiduct. 



D. Branches of the intestine. Ovd. Oviduct. Sp.th. Spermatheca. 



E. Eggs. Par. Parenchym. Sz. Spermatozoa. 



F. Food stocks. P.b. Penis bulb. Te. Left testicle. 

 Gl. Salivary glands. Pe. Penis. Te'. Right testicle. 

 i. Longitudinal muscles. Ph. Pharynx. Ut. End of uterus. 



M Mouth and oral sucker. R. Circular muscles. Tit'. Convolutions of Uterus. 



N. Central nervous system. S. Ventral sucker. Vg. Vagina. 



Oe. (Esophagus. Sh.g. Shell gland. W.v. Water vascular trunk. 



Fig. 1. Gives a general view of the whole animal seen from below. 



Figs. 2-6. Transverse sections at various heights, arranged in their natural succession from in front back- 

 ward. 



Fig. 2. Through the hind end of the oral sucker, to show the central nervous ganglion. 



Fie. 3. Throusrh the two branches of the digestive canal. 



Fig. 4. Oblique section passing through the ovary and the blind end of the right digestive caecum, and 

 the front of the ventral sucker. Of. Fig. 1. 



Fig. 4, A. Transverse section of the penis bulb. 



Fig. 5. Slightly oblique section through both testes. 



Fig. 6. Diagrammatic combination of several sections, to show the origin of the uterus, and its relation 

 to the shell gland and vagina. 



Fig. 7. Through the hind end of the fluke, to show the main water-vascular trunk. 



Fig. 8. Surface view of the lining of the water vascular system. 



Fig. 9. Basement membrane of the body, with the underlying skin muscles. Dr., subcutaneous glands. 



Figs. 10 and 11 represent longitudinal sections. 



Fig. 10. Through the mouth, pharynx and oesophagus, a. prepharyngeal region of the digestive tract. 



Fig. 11. Through the ventral sucker and the penis. 



Fig. 12. Epithelium of the digestive caeca. A. Transverse section. P. Surface view. 



Fig. 13. Connection of the spermiduct and testicle. 



Fig. 14. Cells of the so-called salivary glands. 



Fig. 15. Eggs. A, from the upper, P, from the lower part of the uterus. 



Fig. 16. Egg-foodstock. 



Fig. 17. Longitudinal section of the walls of the oesophagus. 



1 Cobbold. Journ. Linn. Soc., Lond., Vol. xiii, p. 35. 3 Wierzejski. Zur Eenntnisa des Baues von Calicotyle 



- Huxley. Anatomy of Invertebrate Animals. Chap. IV- Kroyeri Dies. Zeitschr. f. wiss. Zool., xxix, p. 550. 



