49 HIRUDO. 
vessel, sometimes as many as fifty being together, whence they disperse 
to establish themselves independently. 
Six weeks after the preceding specimen, apparently so prolific, had 
been taken, the young began to desert it, transferring their abode to ano- 
other specimen in the same vessel. 
Both specimens were found dead two or three weeks subsequently ; 
but with the exception of a few stragglers, all the young had collected 
in agroup on the side of the vessel. ‘They thence dispersed themselves, 
and afterwards died in October. 
The young are sometimes grey, finely speckled or green. They 
swim supine under the surface of the water, though ill adapted for moving 
in such a position. A cluster affixed to the parent has appeared bluish. 
Some adults are greyish green, but their natural colour seems grass- 
green, speckled yellow, and somewhat changeable, and, as above said, the 
colours may be revived, by renewing the element. 
I have found this animal in Coldingham Loch in Berwickshire, and 
in the counties of Edinburgh and Linlithgow. I was indebted to Sir 
Walter Trevelyan, Baronet, for several specimens from the island of Bute. 
Nevertheless the species is rare, and it seems to have disappeared entirely 
from some places where it dwelt a number of years ago, 
Pate IV. 
Fie. 24. Hirudo tessellatata (sew gelatinosa), the Chequered or Gelatinous 
Leech, quiescent, upper surface. 
25. The same active, under surface. 
26. Outline of the head, shewing the position of the eyes. 
27. Margin. 
28. Specimen having fed, back. 
29. The same, belly, shewing the interanea. 
30. The same, enlarged. 
§ 10. Hirupo virrina—TZhe Glassy Leech.—Plate V. Figs. 20, 21, 22. 23. 
Nothing can more favour the study of the naturalist, than an oppor- 
tunity of inspecting the transparent animal, when he beholds the free 
