146 Royal Society : — 



This species is considered by some authors a variety of' the 

 British M. discors. There are, however, certain differences 

 in form, colour, and sculpture which appear to me sufficient 

 to distinguish the two species. The present is a larger species, 

 transversely more elongate and proportionally narrower, the 

 difference in width of the anterior and posterior ends being less 

 marked. The strige on the hinder area, in adult specimens, are 

 distinct only towards the umbones, and gradually become 

 obsolete towards the margin of the valves, which, on this ac- 

 count, are smooth and not denticulated within as in discors. 

 The epidermis of Icevigata is brown on the greater portion of 

 the shell, becoming pale olive or brownish green towards the 

 umbones. 



The figures in Gould's Invert. Mass. 1870, are evidently 

 reversed ; tig. 490, on page 193, represents his idea of discors^ 

 and not the variety Icevigata^ which is figured on the previous 

 page. Whether the American shell is the same as the British 

 species is somewhat doubtful ,• but, judging from Gould's 

 figure and specimens in the British Museum, they appear to 

 be different, the foma being certainly distinct. 



Pecten {Pseudamusium) groenlandicus, Sowerby, 



Thesaurus Concli. i. pi, xiii. f. 40, 



P. vitreifs, Gray (non OhemuiLz), Parry's Voy, 1819, appendix, p. 245, 



Hah. Off Cape Louis Napoleon, 25 fms. ; Hayes Point, 

 35 fms. {Feilden) ; Discovery Bay, 5^ fms. [Feilden and 

 Hart) . 



PROCEEDINGS OF LEARNED SOCIETIES. 



ROYAL SOCIETY. 



Jan. 25, 1877.— Dr. J. Dalton Hooker, C.B., President, in the 



Chair. 



Description of the Living and Extinct Races of Gigantic Land- 

 Tortoises. — Parts III. & IV. The Races of the Aldabra Group 

 and Mascarene Islands. (Conclusion.) Ry Dr. Albert GiJNTHEK, 

 F.R.S. 



In continuation of, and concluding, the researches into the history 

 of the Gigantic Land-Tortoises, read before the Royal Society on 

 June 20, 1874, and published in the 165th volume of the Philo- 

 sophical Transactions, the author treats in Parts III. and IV. of 

 the Tortoises of the Aldabra Group and Mascarenes. 



