64 ZOOPHYTES. 



tomously, so as to terminate in more than ten tubular extremities. Its 

 irregular curvatures, distorted appearance, and umber-brown colour, pre- 

 sented a narrow resemblance to the wonted object of comparison, a minute, 

 microscopic, decaying fragment of some shrub or tree. 



A pure white ascidian hydra issued from each of the extremities, 

 provided with a circular row of 22 or 24 tentacula, as enumerated in two, 

 expanding like a funnel, half a line in diameter. These organs are com- 

 pletely flexible, endowed with percussive action, clasping across each 

 other like so many fingers of both hands, attracting and repelling particles 

 in their vicinity, all indicating a ciliated structure. Sudden exposure to 

 the light invites the ascent and display of the hydrse, the tentacula sur- 

 rounding a low projecting lip in the centre. 



No cellular enlargement distinguishes the extremity of the branch, 

 which is both there, and somewhat lower, sufficiently diaphanous to expose 

 the animal's body, descending as far within the tube as equal to thrice the 

 length of the tentacula. The extremity of the branch being simply tubu- 

 lar, closes as an ovoidal bulb when the hydra is retracted, and relaxes as 

 it protrudes. During its retreat, the bulb is susceptible of slight inflexion 

 to either side. The hydra is very vivacious, it withdraws instantaneously, 

 when the ovoidal summit closing above ensures its safety below. 



This specimen occurred in the beginning of August, on the under 

 surface of a stone, in a brook flowing through the parish of Foulden into 

 the river Whitadder in Berwickshire. 



Ten hydra? were displayed at the same moment, though the specimen 

 might have been circumscribed by a circle of six lines in diameter. Seven 

 of them survived during five weeks. Meanwhile it was suspended by a 

 hair, as its delicacy required, in a vessel of water. 



But it suffered such injury by conveyance fifty or sixty miles, that 

 only a portion remained entire for microscopical inspection and delineation. 



Notwithstanding an anxious search, repeated during several succes- 

 sive years, both in the same place and in the vicinity, no other specimen 

 could be discovered. 



Vol. I. Plate XII. Fig. 12. Tubularia sultana. 



13. The same enlarged. 



