﻿23. RENILIA. 35 



Renilla americana, Lamh, A. s. V. ii. 429. 



Renilla americana (spicula), Quekett, Lectures Hist. ii. p. 133, f. 69, 



G, H. 



Alcyonium agaricum, Gmel. S. N. p. 3811. 



Eenilla americana, Schweig. Beob. p. 23, t. 2. f. 10 ; Elirenb. Corall. R, 



M. ; Blainv. 3Ian. cPAct. p. 528 ; Dana, Zooph, p. 588, t. 57. f. 1, la. 

 Eenilla reniformis, Chivwr, R. A. ed. 2. p. 319 ; Herklots, Not, p. 28, 



t. 7, f. 1 ; Gray, P. Z. S. 1860, v. p. 24. 



Hab. Coast of Brazil, Bay of E.io Janeiro ; West Indies. 



"Frond rounded, reniform, or heart-shaped, a little longer than 

 broad. Sinus extending about one-third across the disk, rounded 

 within, the posterior lobes meeting, or overlapping somewhat behind ; 

 peduncle well-developed, bulbous at the end, and enlarged where it 

 joins the disk to form, in part, the dorsal cavity of the disk. Lower 

 surface of the frond nearly smooth, but marked with fine radiating 

 striae, filled with small spicula, and with a network of light-coloured 

 lines. Cells few, rather large, surrounded by small and slightly 

 prominent spicula; rudimentary individuals numerous, irregularly 

 scattered among the cells, a little prominent, composed of eight or ten 

 little lobes. Colour of the disk, when living, according to the draw- 

 ings of Prof. Agassiz, a vivid reddish purple. Peduncle the same 

 colour, except at the tip and point of union with the disk, where it 

 is lighter ; polypes diaphanous, delicate bluish white, the walls with 

 specks §f brown, and a circle of brown spots just below the tentacles ; 

 tentacles diaphanous, with a marginal line of brown spots on each 

 side beneath, widening towards the base. The polypes are arranged 

 symmetrically on each side of a narrow naked space extending from 

 the sinus more than half across the disk, and situated above the large 

 central chamber within ; when expanded they are much exserted, but 

 less so than in other species of the genus. The tentacles are narrow, 

 lanceolate, with rather distant, long lobes, which are confined princi- 

 pally to the outer half. Mouth oblong, with four small rounded 

 lobes on each side. 



" This species is capable of distending itself greatly with water, when 

 it becomes very thick and swollen, thinnest at the edges j the pe- 

 duncle can expand to four or five times its length when contracted. 

 According to Prof. Agassiz, who has carefully studied it while Uving, 

 it is remarkably phosphorescent, emitting a ' golden-green light of 

 a most wonderful softness.' Its ordinary position, when expanded, 

 is to have the peduncle buried perpendicidarly in the sand, and 

 swollen into a bulb at the end. In locomotion the disk itself can be 

 used, either by alternately contracting and expanding the two lateral 

 portions, or by expanding and extending the anterior end, and then 

 contracting so as to form a transverse constriction which gradually 

 passes off posteriorly (Coll. Mus. Comp. Zool.). It is found quite 

 commonly at low-water mark and in pools left bj^ the tide on the 

 coast of Georgia and South Carolina, extending as far northward as 

 Beaufort, N. C'—Verrill, Mem. Boston Soc. JV. H. i. p. 15. 



d2 



