56 



to the circumference, and covered with a firm cellular, 

 coriaceous or cretaceous covering*." 



The number of tentacula are said to vary in different 

 species, but M. Lamouroux only examined the polypes of 

 Alcyonium lobatum, and found them not to agree with those 

 attributed by Dr. Solander and Dr. Spix to this species. 



In the following catalogue, as in that of the sponges, 

 the most obvious characters, and those which are most likely 

 to be detected in the fossil, are particularised. 



1. Alcyonium arboreuni. — With papillary pores, disposed in 



lateral and terminal tuberosities. — 

 Gmelin^ p. 3810, n. 1. 



2. A, palmatiun With a simple stem, subramose, and 



papillous at the extremity. — Mar- 

 silli, Tab. xv. n. 74, 75. 



3. — lobatum With a grey, tuberous crust; lobated; 



with numerous impressed pores. — 



1. A. digitatum, or dead man's toes of Ellis, Cor. Tab. xxxiii. a. . A. a. 



2. A. exos, Spinx, An. du Mus. Tom. xiii. Tab. xxxiii. fig. 8 to 14. 



4. — rubrum. 



cydonium.. 



massa,^ 

 cidaris. 



-Red, soft, and encrusting ; entirely 

 covered with points or stars with 

 eight rays. 



-An oval or elliptical mass, convex above, 

 concave beneath, irregularly grooved 

 and notched ; cells discoverable, if 

 the skin is not injured. 



Jrregularly shaped. 



^Fixed, globose, and hard ; excavated 

 by tortuous sinuses ; terminal de- 

 pression large ; frequent, small, sub- 

 stellated openings. — Donat. Adr, 

 p. 56j Tab ix. 



* Histoire des Polypiers Coralligenes flexibles, &c. par J. V. F= 

 Lamouroux, A. Caen, 1816, p. 317. 



