324 



Annelides. 



On the Minute Anatomy of the Horse-Leech, Hirudo sanguisorba, 

 (Sav.), H. vorax (Johnst.) By John Quekett, Esq., M.R.C.S.L. 



(Continued from p. 94). 



rig. 1. Nervous system of Hoi-se-leech. The first incrassated portion of the nervous cord represents 

 the brain, the rest ganglionic enlargements. Fig. 2. Plan of ventral blood-vessel according to Dr. Raw- 



lins Johnston. The outer black line represents the ventral vessel ; the inner line the nervous cord enclosed 

 in it. Fig. 3. Head of the horse-leech, showing the arrangement of the eyes. Fig. 4 Nervous 



ganglion magnified 200 diameters. Fig. 5. Portion of integument of abdomen, showing four openings 



of the mucous vesicles. Fig. 6. Magnified view of Respiratory Apparatus, a. lateral vessels. &. loop- 



shaped gland, c. mucous vesicle. Fig. 7. Eye witfi choroid coat entire. Fig. 8. Eye with.choroid 



coat partly removed. Fig. 9. Respiratory system of the Horse-leech. 



The venous system of the horse-leech is represented by two vessels 

 with their communicating branches, one situated on the dorsal, the 

 other on the ventral aspect of the body. They are both much smaller 

 than the lateral vessels which have been previously described ; and 



