oj Edinburgh, Session 1871-72. 615 
The following Gentlemen were admitted Fellows of the 
{Society : — 
David Maclagan, Esq., C.A. 
Major Rickard. 
Dr John Sibbald. 
Dr J. G. Fleming. 
Rev. Andrew Tait, LL.D. 
David Grieve, Esq. 
The Right Rev. Bishop Cotterill. 
George Barclay, Esq. 
Monday , 29 th January 1872. 
The Hon. LORD NEAVES, Vice-President, in the Chair. 
The following Communications were read : — 
1. On the Wheeling of Birds. By Professor Fleeming 
Jenkin. 
2. Notice of a New Family of the Echinodermata. By 
Professor Wyville Thomson, LL.D., F.R.SS.L. and E., 
F.L.S., F.G.S. 
During the deep sea dredging expedition of H.M. ships 
‘Lightning’ and ‘Porcupine,’ in the summers of 1868-69 and 
1870, two or three nearly perfect specimens, and a number of frag- 
ments were procured of three species of regular echinideans, which 
were referred by the author to a new family, the Echinothuridae, 
intermediate in their more essential characters between the 
Cidaridae and the Diadematidae. 
In these urchins the test is circular and greatly depressed. The 
plates of the perisom are long and strap-shaped, and the inter- 
ambulacral plates overlap one another regularly from the apical 
towards the oral poll, while the ambulacral plates overlap in a 
similar way in the opposite direction. The test is thus flexible. 
The plates of the ambulacral areae are essentially within the inter - 
ambulacral plates which over-lie them along their outer edges. 
The ambulacral pores are tri-gem in ah arranged in wide arcs; the 
