On two kinds of Australian Leeches. 37 



sac or capsule of $te cocoon. The two magnified ends of the 

 capsule are seen in Fig. 7. 



The so-called Australian horse-leech is represented in Fig. 

 10,* showing the upper part of its body, where there is only one 

 longitudinal black line in the middle of the back ; while the 

 rest of the leech, above and below (Fig. 11), is of an uni- 

 form dark rusty color. The body of this species has only 94 

 rings, which are not longitudinally divided (as seen in Fig. 5), 

 but have large, irregular folds, of no distinct character (Fig. 

 13, magnified). The horse-leech has five pairs of eyes (Fig. 

 12, magnified), but has the same number of pores on the 

 under-side of its body as the medicinal leech. 



The tenacity of life which leeches of these two kinds have 

 shown, while under my examination, is worth noticing. To 

 enable me to make exact drawings, and to observe correctly, 

 it was necessary, to keep the animal quiet, but it was also neces- 

 sary to avoid the risk of a change in the color and other essen- 

 tial characters of the animal, by death. Sulphuric ether was 

 therefore tried, no chloroform being at hand ; but, a wrapper 

 of linen, fully saturated with the ether, was found to be in- 

 effective. It was necessary to plunge the leech in a vessel 

 full of that fluid ; and, even after a few minutes immersion, 

 the further addition of strong spirits of wine was required to 

 render the animal motionless. By this time, however, it 

 appeared actually dead ; a good deal of leech-blood was dis- 

 charged, and the body was covered with a thick layer of the 

 mucous substance. In this state it was cleaned and laid under 

 the microscope. The process of observing and drawing had 

 been continued for an hour or so, when the eyes, or rather 

 the eye-lids (if that expression might be used), were observed 

 to be in a peculiar opening and shutting motion, by which, 

 each time, a minute drop of a fluid was squeezed out. The 

 same operation was performed afterwards by the eighteen 

 pairs of pores, which are in connection with glands yielding 

 the mucous matter ; but this time they discharged sulphuric 

 ether and alcohol which had entered the body, and very little 

 of the mucous matter was perceptible. The leech was again 

 placed in fresh water, and, after a very short time, it swam 

 about as if nothing had happened. The horse-leech, especi- 

 ally, showed this great power of resisting destructive influ- 

 ences from without, which, perhaps, may be attributed to the 

 greater mass of mucous matter it is able to surround itself with. 



Having put the specimens under observation into a bottle 

 full of strong spirits of wine, they soon died ; and here I 



