38 REPORT ON THE PENNATULIDA. 



substance, is thinner than in Funiciilina, from which it differs further 

 in being very closely beset with the characteristic red calcareous 

 spicules (Figs. 3, 4, 5 /). These spicules are of very various sizes and 

 placed in different directions, though usually with their long axes more 

 or less parallel to that of the polypes ; their shape and other characters 

 will be described farther on. 



The partition walls between the several polypes of a leaf have the 

 same structure as the external body-wall, but are very much thinner, 

 the mesoderm being hardh' thicker than the cellular endoderm 

 clothing it ; they are also devoid of spicules (Fig. 5). These partitions 

 are, so far as we have been able to determine, imperforate, so that the 

 body cavities of the several polypes are completely separated from one 

 another, and in this respect our observations accord with those of 

 KoUiker on PcniwUila. though in the allied genus Pteroeides he has 

 shown that wide apertures exist in the septa, thus placing the polypes 

 in direct communication with one another. 



The bottom of the polype cavity is separated from the dorsal or 

 lateral canal of the rachis by a very thin wall (Figs. 3 and 4), and the 

 cavities of the ventral polypes appear to communicate with the 

 meshes of the spongy connective-tissue of the rachis-wall. 



The free oral ends of the polypes have thicker walls than the parts 

 which are fused to form the leaf ; and these free ends are strengthened 

 by numerous very large and stout spicules, whose direction is mainly 

 longitudinal. 



The longitudinal muscles of the rachis are not prolonged into the 

 leaves, the muscular system of which is extremely feebly developed. 



//. Hie CiiJij.v. — As in FunicuU)ui, the calyx (Figs. 8 and 4 fj h) is 

 produced into eight hollow processes, alternating with the tentacles. 

 These processes are longer and more pointed than in Funiculina, and 

 are stiffened by very numerous spicules, many of which are of very 

 large size ; indeed the spicules are both more abundant and of greater 

 size in the calyx than in any other part of the ^Dolype. In most of the 

 polypes the ends of the spicules project freely beyond the ends of the 

 processes for a short distance ; but this condition is almost certainly 

 to be ascribed to the action of the spirit in which the specimens are 

 preserved having caused the fleshy bodv substance to contract and so 

 leave the ends of the spicules bare. 



When the polypes are retracted, the calyx processes are by the 

 action of the retractor muscles (Fig. 6 j)) pulled in towards one another, 

 and meeting in the middle form a pointed conical cover completely 

 protecting the entrance to the polype cavity (Fig. 3). 



The calcareous spicules, which form so characteristic an element 

 in the structure of /'eyinatula, may be described here. They occur in 

 great numbers along the whole length of both upper and under surfaces 

 of the leaves, being more closely placed along the lines of division 

 between the component polypes (Fig. 5) than at the intervening 

 portions. In the free oral ends of the polypes, and especially in the 



