CORALLIFERI. 405 
jecturally referred to the Coralliferi, few are more singular than the 
Acetabula, or 
ACETABULUM, Lam. 
Where we find a slender and hollow stem supporting a round thin 
plate, like a parasol, with radiating striz, cranulated at the edge 
and having a little smooth disk surrounded with pores in the centre. 
No Polypi can be discovered in them. The rays of the disk are 
hollow and contain greenish granules, a circumstance which led 
Cavolini to consider them as plants(1). : 
One of them—Tubularia acetabulum, Gm.—Donat., Adri., 
III; Tournef., Ins. CCCXVIII(2), is found in the Mediterra- 
nean. 
Potypuysa, Lam. 
Where, as in the preceding, we find a hollow and slender stem, 
but which bears on its summit a bundle of little closed vesicles in 
place of a disk formed of tubes(3). 
FAMILY III. 
CORTICATI. 
This family comprises genera in which all the Polypi are 
cornected by a common, thick, fleshy or gelatinous substance, 
A 
(1) Icannot find the openings round the circumference mentioned by M. de 
Lamarck. The tubes which form the raysare closed. The pretended tentacula 
described by Donati were foreign bodies. Neither the Acetabula nor Polyphysa 
are vaginiform Polypi. 
N.B. Since the first edition of this work, M. Rafeneau, of Lille, has presented 
a Memoir to the Academy, in which he considers the Acetabulum as a plant, 
belonging to the family of the Conferve. 
(2) Add the Acétabule petit godet, Zool. de Freycin., pl., xc, f. 6, 7. 
(3) Pol. aspergillum, Lamour.; Sol. and Ell., App., pl. 69, f. °2—6, or Fucus 
- peniculus, D. Turner, Fuc., IV, pl. 228. 
