334 Proceedings of the Boyal 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 Holothuria, it 

 would be premature, it appears to me, to describe it as a new 

 species. 



Explanation of Plate XVI. 

 Fig. 1. Holothuria, 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 R. I. Shearer, Esq., Wick. 

 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 



