CONTENTS. 
Page. 
XL. — Notice of a Specimen of the Larm ehurneuSy 
or Ivory Gull, shot in Zetland ; and further Re- 
marks on the Iceland Gull By L. Edmondston, 
Esq. 501 
XLI. — Observations on the Formation of the various 
Lead-Spars. By Mt James Braid, Surgeon. - 508 
XLI I. — Description of a New Species of Larus. By 
Dr Traill. - - 514 
XLIII. — 'Remarks on the Specific Characters of 
Birds. By Mr W. Macgillivray. - - -517 
ILIAN.— Notes on the Geognosy of the Crif- Felly 
Kirkhean, and the Needle's Eye, in Galloway. By 
Professor Jameson. ------ 541 
XIN .-—Observations mi the Anatomy of the Beaver, 
(Castor Fiber, Linn.) considered as an Aquatic 
Animal. By Dr Knox. ----- 548 
XL VI. — Speculations in regai'd to the Formation of 
Opal, Wood-stone, and Diamond. By Professor 
Jameson. 556 
XLVII. — Map of Mackenzie's River. By Mr W. 
F. Wenzel. - 562 
XLVIII. — Observations on some Species of the Genus 
Vermiculum of Montagu. By the Rev. Dr Fle- 
ming. 564 
XLIX. — Notes in regard to Marine Shells found in 
the Line of the Ardrossan Canal. By Capt. Laskey. 568 
APPENDIX. 
History of the Society, - - - - -^571 
List of OJice-Bearers for - - -586 
List of Members, continued from Vol. III. - - 587 
Index, - 591 
