Alcyonium. Z. ASTEROIDA. 189 



examined, are seen to be divided into eight rays, indicating the num- 

 ber of the tentacula of the polypes, which issue hei'e. The body of 

 the polypes is as it were enclosed in a transparent vesicular mem- 

 brane, dotted with many minute calcareous grains, and marked with 

 eight white longitudinal lines or septa which, stretching between the 

 membrane and the centi'al stomach, divide the intermediate space in- 

 to an equal number of compartments. These lines not only extend 

 to the base of the tentacula, but run across the oral disk, and termi- 

 nate in the central mouth. The tentacula are short, obtuse, ciliated 

 on the margins, and strengthened at their roots by numerous linear 

 straight crystalline spicula. From the base of the white longitudi- 

 nal lines an equal, number of white tortuous glandular filaments de- 

 pend, hanging loose in an abdominal cavity placed underneath the 

 fleshy cylindrical stomach, and continuous with the aquiferous canals.* 

 The Polype-cells are oval, placed just under the skin, and are the ter- 

 minations of the long aquiferous canals which run through the whole 

 polypidom. These canals divide in their course into branches that 

 diverge towards the circumference where they dilate into the cells ; 

 they have strong cartilaginous, perhaps muscular, coats ; and are fil- 

 led with a much less consistent matter than that of the body of the 

 polype itself. It appears, from this disposition of the tubes, that many 

 polypes communicate together and form a compound animal, but that 

 all the polypes of the same polypidom do not communicate directly 

 by their medium. The space between the tubes is occupied by a 

 loose fibrous net-work, and the threads being a little more crowded at 

 particular places, they form lozenge-shaped compartments within which 

 are smaller meshes ; and the interstices of the whole are filled with a 

 transparent gelatine, in which numerous crystalline irregular spicula 

 lie immersed. These spicula are mostly in the form of a cross and 

 toothed on the sides, but they have no organic connection either with 

 the reticular fibres or with the tubes : they are calcareous, for if a 

 portion of the zoophyte is immersed in a mineral acid, a strong effer- 

 vescence immediately takes place, and spicula are no longer discernible. 



* A classical friend on seeing the specimen from which our figure was taken 

 in full expansion, when it is translucent and permits a view of the interanea, 

 was reminded of the following lines : 



" In liquidis translucet aquis ; ut eburnea si quis 

 " Signa tegat claro, vel Candida lilia, vitro." 



" salientia viscera possis 



" Et perlucentes numerare in pectore fibras." 



Ovid. Met. vi. 354 and .390. 



