85 



than of Trochus. It is to be grouped with S. dealhalum^ Hinds, 

 which it closely resembles. It is also similar in form, color, and 

 size to Margarita ohscura, Couthouy. Perhaps it would come 

 under the genus Torinia, Gray. 



Dr. Gould presented to the Society an imperfect speci- 

 men of Anodon gigaiitea, Middendorff, from the river 

 Onon, northern Siberia, received from the describer. It 

 was 1 1 inches long, and 6} high. 



Dr. Cabot exhibited to the Society the following birds, 

 new to the collection, which had been recently mounted for 

 the Cabinet ; viz., Picus auratus, male, presented by Wm. 

 Minot, jr. ; Aix sponsa, male, presented by Mr. Robert 

 HoW ; Mergus serrator, female, presented by Mr. F. H. 

 Jackson ; Ortygometra carolinensis, presented by Mr. 

 Nathan Robbins ; Fuligula marila, male, presented by 

 himself; Mergus cucuUatus, young male, purchased in Bos- 

 ton Market ; Picus pileatus, male ; Andus , Tetrao 



rupestris, male, from Newfoundland ; and Astur cooperi, 

 female, received in exchange. 



December 6, 1848. 

 Dr. C. T. Jackson, Vice President in the Chair. 



Present, nineteen members. 



Mr. Desor gave an account of his investigations to ascer- 

 tain the true character of the ovarian egg. He stated that 

 up to the present time the yolk had been regarded by em- 

 bryologists as a homogeneous, granular mass. This has 

 been considered its fundamental character. Mr. Vogt, in 

 studying the embryonic development of the Salmonidce, 

 had noticed that in the ovarian egg the granules of the yolk 

 showed a disposition to accumulate around the germinative 



