364 ON THE ANATOMY OF A SUPPOSED NEW SPECIES 



round the stomodoeal opening is a prominent ridge, in the depression round which 

 lie the openings of the introverted tentacles (Figs. i. and il.). 



Coenosarcal canals and mode of budding. The mesenteries are 48 in numbei 

 and have a determinable position in respect to the 24 septa. There are 48 inter- 

 mesenterial spaces, 24 enfocoelic between mesenteries of the same pair, into which the 

 septa project, and 24 exocoelic spaces between mesenteries of neighbouring paLrs\ From 

 each intermesenterial space is given off a coenosarcal canal passing outside the theca. 

 The dividing walls of these are continuous with the mesenteries over the theca, and 

 indeed may be regarded as their perijjheral ends or extrathecal portions (Figs. I. and II.). 

 The coenosarcal canals end blindly at the free edges of the colony, but in the central 

 parts they put each intermesenterial space of each several polyp into communication 

 with at least one such space in a neighbouring polyp. 



Budding takes place from the blind ends of the coenosarcal canals at the basal 

 margin of the single jwlyp or colony. A number of the coenosarcal canals fuse together 

 and a mouth breaks through. The intermesenterial spaces of the daughter polyp on the 

 inner side, i.e. towards the parent polyp, are each formed directly from a single 

 coenosarcal canal, while those at the sides are formed by the branching of these canals. 

 The mesenteries are formed from the dividing walls of the coenosarcal canals, i.e. from 

 the extrathecal portions of the mesenteries of the parent polyp. The young corallite 

 appears to be very rapidly formed, and has from the first a diameter of 2b mm.' 



The intermesenterial spaces, besides being in communication w^th the coenosarcal 

 canals over the theca, have also connecting canals through the theca. The dividing- 

 walls of the coenosarcal canals outside the free portions of the corallites are attached 

 to the skeleton between the costae, which project into their lumina. The mesenteries 

 on the other hand have their broad bases attached to the septa close to their fusion 

 into the theca, and hence somewhat facing one another. The connecting canals near 

 the top of the theca from the exocoeles run straight through the theca near the 

 base of one of the bounding mesenteries and open into their corresponding coenosarcal 

 canals (Fig. I., b). In the entocoeles the arrangement is similar in the same position, 

 but the connecting canals often arise at a considerable distance up the sides of the 

 septa and perhaps run diagonally through them. This arrangement of connecting canals 

 near the top of the theca, joining the intermesenterial spaces with their corresponding 

 coenosarcal canals alone, strongly supports the view that in this species the theca is formed 

 simply by the fusion of thickenings on the sides of the septa. Lower down in the 

 polyps instead of separate connecting canals, a system of ramifying and anastomosing 

 canals is found, similar to that described by Fowler for Rhodopsammia (7), but not 

 so complicated, owing probably to the more delicate corallum. 



1 There would thus be between neighbouring primary septa, in each system 8 mesenteries, 2 primary, 

 2 secondary, and 4 tertiary. In one poln^ however in one system tliere were 10 mesenteries owing to an 

 addition of 2 tertiary, hut the next system had ouly 6 mesenteries, 2 tertiary beiug absent. 



- In the various colonies in the collection I have only found one bud without a corallite, and in this 

 the preservation was not sufficiently good for me to follow out the process in any detail. I have traced 

 however the connections of two buds, each of about 3 mm. in diameter, with the parent polyp. 



