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Monday^ Sd February 1851. 

 Sir T. M. BRISBANE, Bart., President, in the Chair. 



The following Communications were read : — 



1. On some new Marine Animals, discovered during a 

 cruise among the Hebrides with Robert Macandrew, 

 Esq., of Liverpool, in 1850. By Professors Edward 

 Forbes and J. Goodsir. Communicated by Professor 

 Goodsir. 



The animals either wholly new, or new to Britain, described in 

 this communication, were taken during a yachting cruise with Mr Mac- 

 andrew, of Liverpool, among the Hebrides, in the month of August 

 1 850. During this voyage, which lasted three weeks, a series of obser- 

 vations were conducted by means of the dredge and towing-net. Not 

 a single new testaceous Mollusk was procured ; but several remark- 

 able Ascidians and lladiata were discovered, some of them so curious 

 in themselves, and so important in their zoological bearings, that 

 the authors of this paper thought it desirable to lay an account of 

 them before the Royal Society of Edinburgh. 



The most remarkable of these is the longest compound Ascidian 

 yet discovered in the Atlantic. Its nearest described ally is the 

 genus Diazona of Savigny, between which animal and Clavellma 

 it forms a link. The authors of this paper propose to designate 

 this animal Syntcthys Hebridia, having found it necessary to esta- 

 blish a genus for its reception. The authors have also dredged up 

 the Holothuria iiitestinalis of Ascanius and Rathke, which is the 

 second species of Holothuria proper discovered in the British seas ; 

 the first having being discovered by Mr Peach under the name of 

 " Nigger," given to it by the Cornish fishermen. 



A new species of the curious genus Sarcodictyon, distinguished by 

 the polype cells being grouped in assemblages of from three to five, 

 was described under the designation of S. cojglomcratwn. 



The Arachnactis albida of Sars was found in the Minch. Por- 

 tions of an animal found by Professor Balfour in the same locality 

 in 1841, have now been recognised as belonging to this curious Ac- 

 tinea. 



