12 VERMEL ON THE POLYPS OF THE 



Family Renilldoe Gray (emended). 



Pennahtlinw {pars) Ehrenberg, Dana. Renilleai Gray, Ann. and Mag. of Nat. Hist., v. p. 20 

 (1860). 



Polyps arranged symmetrically on the upper surface of a more or less flattened cavern- 

 ous disk or frond, to the lower surface of which there is attached a hollow locomotive 

 organ, in the form of a peduncle, destitute of a solid axis. 



Genus Renilla Lamarck. 



Alci/onmrn {pars) Linn., Syst. Nat., ed. x. (1758). Pennahila {pars) Pallas (1766) ; Ellis and 

 Sol. (1786). Renilla Lamarck, Hist, des Anim. sans Vert. (1816) ; Blainvllle, Ehrenberg, Dana, 

 Milne-Edwards, etc. HerMotzia Gray, Ann. and Mag. of Nat. Hist, 1860, vol. v. p. 24. 



Frond more or less reniform, with a notch or sinus in the posterior edge ; lower surface 

 somewhat striated with radiating lines ; upper surface with scattered cells surrounded by 

 spicula, which usually project a little above the surface. Polyps when expanded much 

 exsert, but capable of entire retraction. Among the perfect polyps are scattered numer- 

 ous rudimentary individuals, which appear like clusters of small white papillae. The 

 peduncle is attached to the lower surface at or near the sinus ; it is hollow, more or less 

 coriaceous, filled, like the surface of the frond, with calcareous spicula, but capable of a 

 great amount of contraction and expansion ; a membrane divides it into an anterior 

 and posterior longitudinal chamber. Tbe former communicates with a large cavity occu- 

 pying the central and posterior portion of the upper surface, and from this by numerous 

 openings with other cavities, filling the whole interior of the frond, and connected with the 

 polyps. The posterior chamber communicates directly with a large cavity at the origin of 

 the peduncle, and then by means of numerous small openings with the other cavities of 

 the disk. The tentacles have rather long lobes, in a single row on each side. 



The genus HerMotzia of Gray, founded, apparently, on the figure and description of 

 Renilla Edwardm by Herklotz, appears to differ in no respect from Renilla, all the characters 

 assigned to it existing in R. reniformis, the type of the present genus. 



Renilla reniformis Cuvier. 



Kidney-sha}y-d Sea-Pen Ellis, Phil. Trans. 1763, p. 427, pi. 19, figs. 6-10. Pennatula reniformis Pallas, Elencli. Zooph., 

 p. 374 (1766) ; Ellis and Solander, Hist. Zooph., p. 65 (1786). Alcyonium agaricum Linn., Syst. Nat., ed. xii. p. 1294 (1768). 

 Renilla americana Lamarck, Hist, des Anim. sans Vert, t. ii. p. 429, and 2d ed. p. 646 (1816) ; Blainville, Man. d'Actinologie, 

 p. 518 (1834); Ehrenberg, Corall. des roth. Meeres, p. 65 (1834). Renilla americana (pars) Dana, Zoophytes, p. 588 (not the 

 figure, which is R. Dana: nob.) (1846). Renilla reniformis Cuvier, Regne Animal, 2d ed. iii. p. 319 (1830); GmnES. Fauna of 

 S. Carolina (App. to Tuomey's Geol. Survey) no description (1846) ; Agassiz, On the Structure of the Halcyonoid Polypi, p. 10 

 (Extract from the Proceedings of the Am. Association for 1850) (not R. reniformis Herklotz, which is R. Dana: nob.). Renilla 

 americana Milne-Edwards, Coralliaires, t. i. p. 220 (excluding the synonym, R. violaceu Q. and G., which is a distinct species). 



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 over- 

 lapping somewhat, behind ; peduncle well developed, bulbous at the end and enlarged 

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



