Notes on Sula Sgeir and North Rona, with List of Birds. 61 



Fig. 12. Part of one side of a tentacle, showing the cavity and the longi- 

 tudinal muscles. Objective — Swift, 1 inch. 



Fig. 13. Small part of last figure more highly magnified to show muscles, 

 etc. Objective — Zeiss, y^ oil-immersion. 



Fig. 14. Longitudinal section through the wall of the tentacle to show its 

 structure. Objective — Zeiss, -^n oil-immersion. 



Fig. 15. Small portion of the surface of a mesentery in upper part of body. 

 Objective — Swift, | inch. 



Fig. 16. Part of a section through the mesoderm of the body wall, to show 

 the tubules and lacunse. Objective— Swift, ^ inch. 



PLATE III. 



Fig. 1. Part of a transverse section through the upper part of a retracted 

 polype. Objective — Swift, ^ inch. 



Fig. 2. Transverse section of part of the body wall and a mesentery, in 

 lower part of polype. Objective — Zeiss, yV oil-immersion. 



Fig. 3. Transverse section of part of another mesentery to show the muscle 

 fibres. Objective — Zeiss, ^ oil-immersion. 



Fig. 4. Half of a transverse section through the gastric tube, etc. Objective 

 — Swift, 1 inch. 



Fig. 5. Small portion of a tran verse section through upper part of retracted 

 polype. Objective — Swift, \ inch. 



Fig. 6. Another small portion of a similar section, to show the ectodermal 

 cseca. Objective — Swift, % inch. 



Fig. 7. Small part of optical section of a mesentery, showing nerve cells. 

 Objective — Zeiss, ^ oil-immersion. 



Fig. 8. Part of a transverse section through the gastric tube. Objective — 

 Zeiss, ^ oil-immersion. 



II. Notes on the Islands of Sula Sgeir, or North Barra and 

 North Bona, with a List of the Birds Inhabiting them. 

 By John Swinburne, Esq. 



(Read 19th December 1883.) 



In the early part of this season, 1883, as our yacht the 

 " Medina " was lying idle at her moorings, I determined to 

 start for a cruise among the Outer Hebrides, intending to 

 visit, among other places, Hysgeir off Canna, and the Flannan 

 and Shiant Islands — all of them localities which have been 

 made well known to the ornithological world by the very 

 full descriptions that have been given of them by Mr Harvie- 

 Brown. 



Mentioning my intention to my friend, Mr Dalgleish, he 



