8 HIRUDO. 



parity in the size of the capsules of the same group ; but the whole cap- 

 ,sules"of one group are sometimes much smaller than those in another. 

 A general correspondence appears in the form of all. None produced by 

 other leeches, or by any other animals, bear the smallest resemblance to 

 them. 



The Skate Leech is very patient of abstinence. Though most vora- 

 cious in the natural state, all subsistence, as already observed, is rejected 

 by it in confinement, although in such a condition it survives a long time. 



It occasionally seems to die of repletion from previous excesses. A 

 large specimen, taken in the end of June, had suffered a slight injury, pro- 

 bably from pressure in detaching it. In three days it sickened, and at the 

 upper part rent asunder. The animal had burst ; when the whole cavity 

 of the animal was discovered to be occupied by a mass of clotted blood. 



Another specimen proved extremely turgid in autumn, when taken, 

 which I ascribed to the blood which it had absorbed. But, the continued 

 distension during four or five weeks, induced me rather to conjecture that 

 it was owing to the enlarging of the ovarium. In a few days, however, 

 the discharge of a quantity of blood, partly clotted, proved the true 

 cause. The animal then lost its adhesive faculty : it died, and I found 

 it quite straight and rigid, extending far over the edge of its vessel. 



Two large specimens having been obtained on the 7th of July, 

 were preserved for delineation, because there was a considerable diffe- 

 rence in their appearance. One was so' turgid that the papillae of the 

 surface were almost obliterated. Nevertheless, it remained in health, and 

 discharged a copious stream of bloody matter eighty-four days after- 

 wards. 



The Skate Leech is not rare. 



PLATE I. 



FIG. 1. Hirudo muricata The Skate Leecli ; head, a ; sucker, J. 



2. Parasites, Udonella adhering to the neck. 



3. The same, enlarged. 



4. Another, natural size, 

 o. The same, enlarged. 



