The Hirudinea of Illinois. 547 



Macrobdella decora. 



Fig. 22. The male organs dissected and viewed from the right side. 

 The left sperm-duct has its natural position, the right has been displaced 

 upwards. The dotted line indicates the form of the atrium before the 

 removal of a layer of muscles and prostate glands. X 4. 



Fig. 23. The greater part of the reproductive organs dissected and 

 viewed from above. From a specimen from the Fulton Lakes, New 

 York. X 4. 



Plate XLV. 



Fig. 24. Hcemopis marmoratis. Diagram of the entire dorsal annula- 

 tiou, showing also the sensillae, eyes, etc. X 2. 



Fig. 25. Hcemopis lateralis. Surface view of denticles of median 

 jaw. X 112. 



Fig. 26. Hcemopis marmoratis. Reproductive organs dissected and 

 partly displayed in dorsal view. The female organs are shown nearly 

 in situ; the atrium with the left ductus ejaculatorius and epididymis has 

 been displaced far to the left and only a portion of the right ductus is 

 shown; three testes of the left side are included. X 3.5. 



Fig. 27. Hcemopis lateralis. Reproductive organs dissected and dis- 

 played as in figure 26. The ovaries and oviducts are displaced to the 

 left, but the proper position of the left ovary is indicated in outline (ov r ). 

 The atrium is withdrawn somewhat to the right and the epididymes and 

 ducti ejaculatorii of both sides are shown, as well as the anterior end of 

 the right vas deferens and the first testis. X 3.5. 



Plate XLYI. 



Fig 28, 29, 32. Hcemopis lateralis. Dorsal, ventral, and left lateral 

 views respectively of the anterior eight (-)-) somites. X 5. 



Fig. 30, 31. Hcemopis lateralis. Right lateral and dorsal views 

 respectively of the posterior end. X 5. 



Fig. 33, 34. Hazmopis marmoratis. Respectively left lateral and 

 ventral views of somites I to VIII and part of IX. 



Plate XLV II. 



The three figures of this plate represent similar dorsal views of dissec- 

 tions which were selected because of the equality in size and apparent 

 equality of sexual activity of the individuals. In each case almost 

 exactly the same extent of body is. represented, as indicated by the 

 numbered ganglia, and the somites containing the testes are omitted. 

 All, X 7.5. 



Fig. 35. Erpobdella punctata. The left ovary and the right sperm- 

 duct have been removed. 



Fig. 36. Dina fervida. 



Fig. 37. Dina microstoma. 



