370 ON THE ANATOIY OF A SUPPOSED NEW SPECIES 



Mucous cells are scarce, but the epithelium is in places crowded with goblet-like 

 vacuoles with numerous interstitial nuclei towards the exterior (Fig. 11). They are 

 commonly much swollen with some apparently fluid unstainable secretion, and no nuclei 

 especially belonging to them are visible. These secreting vacuoles are found principally 

 opposite to the attachments of the primary and secondary mesenteries. Indeed in some 

 polj'ps they form well marked lines over these mesenteries, extending up almost to the 

 mouth of the stomodoeum. In one specimen, in which a Copepod is lying partially 

 in the stomodoeum and partially in the coelenteron, the vacuoles are much smaller 

 and generally appear to have discharged their secretion. 



Mesenterial filaments (Figs. 12 and 13). The mesenterial filaments of the 

 primary and secondary mesenteiies are the direct continuations of the lower edge of 

 the stomodoeum and have a very similar structure to that described by Bourne (3) 

 and Fowler (8) for other Madreporaria. They are of a somewhat crescentic shape in 

 transverse sections (Fig. 12) and their epithelium is sharply marked off fi-om that of 

 the mesentery below them. The structureless membrane of the mesenteries ends in a 

 T-shaped swelling with numerous fibres passing off into the filament from its ends. 



The central part of the filament is crowded with goblet vacuoles and is the 

 " Driisenstreifen " of the Hertwigs (14) and other German authors. This gradually passes 

 at the sides into an elongated columnar epithelium, which bends round the structureless 

 membrane so that it covers the whole underside of the horizontal bar of the T. These 

 parts correspond to the lateral lobes or " Flimmerstreifen," described b}' the Hertwigs in 

 the Actiniaria and by E. B. Wilson (27) in the Alcyonaria. Mucous cells are more 

 abundant than in the stomodoeum and lie principally at the sides; small glandular 

 vacuoles densely crowded with relativeh' large granules are found also in the same 

 position, but vary very largely in abundance in different polyps. Nematocysts do not 

 become numerous until the convoluted portion of the filament commences, when the 

 goblet vacuoles gradually decrease and finally disappear (Fig. 13). Near the stomodoeal 

 end of the mesenteries the nematocysts lie almost entirely at the sides of the filament, 

 but towards the base they occur in dense masses thi-oughout. 



The filaments of the tertiary mesenteries, as in Fungia, are very similar to those 

 of the primaries and secondaries but slightly smaller. The goblet vacuoles are not 

 nearly so numerous, and do not form a well marked clearer area in the centre. 



Mesenterial Nematocysts (Figs. 14 — 19). The nematocysts of the mesenterial 

 filaments are about '033 mm. in length, and are found in every stage of development. 

 They differ from the tentacular nematocysts in that they are relatively much broader, 

 and are from the youngest stage of about the same size as the ripe nematocvst. 

 The thread is much thicker with fewer coils, and its lower part, when ejected, is 

 formed by an eversible portion of the cell. The structure of the ripe uematocyst 

 (Fig. 14) is very similar to that of the nematocysts from the stomodoeum of Euphi/llia, 

 described and figured by Bourne (4), and those of Caryoplnjllia by Mobius (20) and 

 Iwanzoff (17). The eversible portion is never so long as in Curyophyllia, and is not 

 indeed usually more than about one-third the length of the whole cell (Figs. 14 and 17). 

 The end of the thread projects in the centre of this to the somewhat pointed extremity 

 of the cell. Ai'ound the eversible base is a single spiral row of short hairs, with about 



