4 ZOOPHYTES. 



about four and a half in breadth. They are generally founded on empty 

 shells, likewise on some with living tenants. 



In referring to specimens as the finest, I mean those selected from 

 many occurring in the Scotish seas. — Plate I. 



The leaf of this zoophyte is as thin as paper. — Plate II. fig. 1. One 

 side only is composed of slipper-shaped cells, which are not all of equal 

 dimensions, but presenting a remarkable and an agreeable arrangement to 

 the eye. The opposite side or back of the leaf, exhibits convexities cor- 

 responding with the bottom of the cells, also arranged with considerable 

 regularity, as circular arcs ; but the peculiar order and form not being 

 alike evident as in the cells of the surface. The shape of the cell itself 

 may be compared to that of a violin, consisting of back, breast, and sides, 

 with an internal vacuity. Its figure is best exposed when empty, or when 

 the leaf is partly in decay. A short circular arc, level with the surface, 

 shews the orifice of the cell near its broader end. — Plate II. fig. 4. 

 An ascidian hydra, provided with about 22 tentacula, inhabits the cell, to 

 the side or bottom of which it is affixed by a number of ligaments. 



In younger specimens, where the leaf is clear and transparent, nor 

 exceeding four or five lines in height, the short circular arc, near the 

 broader end, distinctly marks the orifice, and the form and position of the ani- 

 mal are admirably displayed. While quiescent it is seen doubled on itself, 

 like an intestine ; if rising to the orifice of the cell, the tentacula are un- 

 folded as the ribs of a cup of variable width and depth, according to their 

 purpose, or the animal's sensations. Much vehement action follows. They 

 clasp together in various forms ; and exercise a lively percussive faculty ; 

 or the whole head strikes gently, as if against the water. — Fig. 5. 



Now, the entire surface of the leaf seems animated from numbers 

 and vivacious activity : but, during the highest vigour, and the obvi- 

 ous enjoyment of the hydrae in full display, amidst their element, a sudden 

 collapse ensues, they vanish from our sight, and the leaf remains smooth 

 and inanimate. 



The safety of this product is obviously endangered by removal from 

 its native site, even during the short interval of transmission to another, 

 because the retention of more humidity is essential, than is admitted by 



