Messrs Forbes and Goodsir 07t Pelonaia. 29 



16 feet in circumference, and 160 feet in height ; and one spe- 

 cimen which had been blown down, and of which the top had 

 been broken off, measm-ed 88 feet in length, and even at this 

 height was 18 inches in diameter. 



The ascent of the sap in trees is a subject which has long 

 occupied the attention of physiologists. Some difference of 

 opinion, however, exists regarding it, and hitherto it is be- 

 lieved no very definite conclusions have been arrived at ; — and 

 although not strictly connected with the subject of this paper, 

 I may be excused for remarking, that the quantity of sap re- 

 quired to sustain such enormous trees as these I have been 

 describing, and the source and nature of the power by which 

 a supply of fluid is raised and kept up, at the great height of 

 180 feet from the ground, are inquiries which, could they be 

 satisfactorily solved, would form most interesting and instruc- 

 tive additions to our knowledge regarding vegetable physiology. 



On Pelonaia, a New Gelius ofTunicated Mollusks^ with Descrip- 

 tions of two Species. By Edward Forbes, Esq., and John 

 Goodsir, Esq., Members of the Wernerian Natural History 

 Society. Communicated by the Authors. With a Plate.* 

 Among the Ascidian Mollusca which we have collected 

 together, with a view to a complete investigation of the Bri- 

 tish Tunicata, are two remarkable animals, which appear to 

 represent a very natural genus as yet unrecorded. They dif- 

 fer from their allies in the tribe chiefly by their not being 

 fixed, and by their form, which reminds one more of that of 

 a Sipunculus than of an Ascidia ; indeed they may be re- 

 garded as analogues of certain Sipunculida?, and in that point 

 of view the details of their forms and structure are of much 

 interest to the naturalist. 



They are both of a cylindrical shape, having their orifices 

 on the same plane, elevated on papillose eminences at one ex- 

 tremity of the body. No rays or t^ntacula surround either of 

 the orifices. The posterior extremity of each terminates in 

 a blunt point. They live buried in mud, quite unattached to 

 any other body, and are extremely apathetic animals, present- 

 ing scarcely any appearance of motion. 



• Read before the Wernerian Natural History Society, April 17. 1841, 



