334 Proceedings of the Royal Physical Society. 
" Feet of twofold structure and figure, some cylindrical, 
dilated at the tip, usually occurring in the abdomen only, 
others situated on the back, not dilated at the tip, emerging 
from warts on the back. Body cylindrical or flattened in 
the abdomen." 
Having only found one specimen of this Eolothuria, it 
would be premature, it appears to me, to describe it as a new 
species. 
Explanation of Plate XVI. 
Fig, 1. Holnthuria, three times the natural size. 
Fig. 2. Buccal extremity and tentacles. 
Fig. 3. Calcareous plates of dorsal feet. 
Fig, 4. „ body-skin. 
Fig, 5, „ „ dorsal feet near head. 
Fig. 6. „ „ oral tentacles. 
Fig. 7. Portion of ventral foot, showing the form and arrangement of the 
plates. 
Fig. 8. Calcareous plates from feet surrounding the head. 
III. Notes on the Ornithology of Caithness. By R, I. Shearer, Esq., 
Ulbster House, and H, Osborne, Esq., Wick. Communicated by 
John Alexander Smith, M.D. 
Part I. — By E,. I, Shearer, ^5^., Wich. 
I have been induced to gather together a full and authentic 
list of all the birds hitherto found in Caithness, the main 
aim being to induce others to exert themselves in this de- 
lightful and interesting study ; and I am confident that, had 
the ornithology of the county been understood and attended 
to by a greater number of persons, a much larger list could 
have been made. The all-sufficient reason I have for think- 
ing so is, that the present list only exhibits twelve additional 
species within the last twenty years ! In particular, that 
portion of the interesting and numerous family, the Syl- 
viadce, comprehending the Warblers proper, is almost utterly 
unknown — the only representatives known to us being the 
reed and wood warblers. This paucity, however, must not 
in any degree be considered as indicative of their absence 
from the county, but must, on the contrary, be ascribed to 
the fact that their haunts are far removed from, and, indeed, 
are forbidden ground to, the ordinary investigator and those 
interested in their economy. Although the northernmost 
