ANTHOZOA ASTEROID A. 145 



we find in the Alcyonium. The skin is coriaceous, strength- 

 ened with calcareous particles, but the interior offers a fibrous 

 net-work containing a transparent jelly in the squares, and 

 permeated with a certain number of longitudinal cartilaginous 

 tubes. The soft part of Pennatula seems more uniformly 

 fleshy or gelatinous, and its polypes are placed only on certain 

 wings or appendages of the polypidom ; but the skin is also co- 

 riaceous, and has moreover in its substance a great number of 

 calcareous spicula placed parallel to one another, and which 

 must greatly add to its consistency and strength. 



The polypes are placed in this external fleshy crust, which, 

 indeed, is but a continuation of their tunic, and serves as a 

 connecting medium to the whole assemblage. Their position 

 in it is marked by an orifice on the surface distinguished by 

 its being cut into eight rays in a starred fashion, and which 

 open when the superior portion of the body is forced out- 

 wards.'"" This exsertile portion, in a state of expansion, re- 

 sembles a cylindrical bladder or nipple crowned with a fringe 

 formed by the eight short thick pectinated tentacula which 

 encircle the mouth. (Plate xxxiv. Fig. 1.) Under this orifice 

 we perceive the stomach, readily distinguished through the 

 transparent parietes by its opacity, occupying the centre of 

 the cylinder, and itself of a cylindrical figure. The space be- 

 tween it and the outer envelopes is divided into eight equal 

 compartments or cells by as many thin ligamentous septa, 

 which, originating in the labial rim, between the bases of the 

 tentacula, descend through the cylinder, attached on the one 

 side to the inner tunic of the body, and on the other to the 

 stomach, which is by this means suspended and retained in its 

 position. The canals or cells formed by these septa commu- 

 nicate freely with the tubulous tentacula above ; and they 

 have a still wider communication with the abdominal cavity 

 underneath the stomach, into which we may observe the septa 

 are also continued for a certain way adhering still to the tunic, 

 but free on their inner edges, for now, instead of septa, they 

 form only the same number of plaits of more or less promi- 



* See on this part of zoophytology Milne- Edwards, Memoires " sur les Alcyons" 

 in Ann. des Sc. Nat. iv. p. 333, &c. an. 1835 : and in the 2de edit, of Lam. Anim. 

 9. Vert. ii. p. 465. 



L 



