dredged up from the Gulf of Manaar. 443 



mounted by an octotentaculated head (fig. 2, a), which is 

 almost colourless, especially towards the centre, and from its 

 more tender nature now, in the dried state, sunk into the 

 calycle, while the firmer wall of the latter thus gives it the 

 appearance of having been truncated. Tentacles composed 

 towards the extremities of small, cylindrical, curved and 

 colourless spicules (fig. 2,f), becoming larger, longer, and 

 tuberculated towards the base (fig. 2,g), where they begin to 

 assume a pink colour, and finally becoming red their tubercles 

 unite with those of the neighbouring spicules, and thus the 

 whole is transformed into the foraminated, fully formed, red, 

 continuous corallum. Calycle charged at the bottom with 

 fragmentary sponge-spicules, which are more or less incorpo- 

 rated with the red substance of the corallum there, and pro- 

 jecting upwards present, when the soft parts above them are 

 removed, an echinated appearance, in which the ends of the 

 spicules are simply branched or otherwise terminated in ac- 

 cordance with their forms respectively (fig. 2, Je). Stolon 

 compressed vertically (fig. 2, b) ; its wall in structure the 

 same as that of the calycle ; its cavity compressed in like 

 manner, so as to be reduced to a minimum, like that in the 

 horizontal plate of T. musica (fig. 2, c). 



Size of specimen described about G-12ths inch long, upon 

 which there are eight calycles at variable distances from each 

 other below l-10th inch. Stolon, of which the growing ends 

 are broken off up to the part where their spicules have become 

 consolidated into the fully formed structure of the corallum, 

 about l-50th inch broad and l-130th inch high, including 

 the walls above and below, which reduces the vertical thick- 

 ness of the cavity to 1-4 50th inch. Calycle about l-36th 

 inch high and l-30th inch broad, including the walls ; a little 

 larger above than below. 



Hab. Marine, on hard bodies. 



Loc. Gulf of Manaar. 



Obs. As before stated, the striking resemblance of this 

 corallum to the test of Polytrema miniaceum in composition, 

 structure, and colour, together with the presence of fragmen- 

 tary sponge-spicules more or less incorporated with the coral- 

 lum, led me to regard it at first as a species of this Foramini- 

 fer ; but subsequent microscopical examination showed that 

 it was almost identical with Tubipora musica, as the above 

 description proves. However, I prefer its insertion here, and 

 alluding to this hereafter by name in its proper place, for the 

 purpose of pointing out its several characters in common with 

 Polytrema, which otherwise might pass unnoticed. 



