TURBINARIJi: PELTIFORMES. 41 



Species 18. Turbinaria patula. (I'ls. VIII. and IX. ; Tl. XXXI. fig. IG.) 



Gemmipora patula, Dana,* Zoophytes, 1848, p. 410. 

 'ITurhimtriafiuiijifunim, Micheliii, Mag. do Zool. Classe, x. (1840) pi. i. 

 Turbinaria hanka; Giebel, Zeitsch. Gcsammt. Naturwiss., xviii. (1861) p. 134. 



Dc^ription.—CoraWma a flat disc in shape, often perfectly circular, with but slight tendency 

 to form folds or protuberances. Margin thinner than in the last species. 



Calicles generally smaller than in T. peltata, either immersed or the margin projects as a 

 thick, well-marked ring of ccenenchyma. Aperture circular. The septa unequally developed ; 

 while the twelve primary are always well developed, the twelve secondary may be developed or 

 rudimentary ; when well developed the tldrd cycle appear as rudiments. Seen from above, 

 the septa project into the aperture more markedly than in the last species, but do not reach 

 the half-radius circle. Seen from the side, the septa slope from the margin and then Ijend 

 sharply to run down towards the columella, limiting a cylindrical or more often funnel-shaped 

 fossa. The columella is very protuberant, sometimes standing up almost finger-like or 

 knobbed, the knol) being free of the septa. The interseptal loculi are well marked, oblong or 

 square. 



The ccenenchyma both above and below is deeply furrowed by elegantly gjrating 

 channels, often running parallel with one another. 



I am in great doubt as to the validity of this iyV^. Although corals are included under it 



which differ sufficiently from T. peltata, they are connected with that type by numerous 



transition forms. The distinctions usually given, viz. the thinner margin and smaller calicles, 



are insufficient, in view of the great variation which exists in these respects. In the 



diagnosis of the species given above, I have found it necessary to lay stress upon other 



more important differences. But even in these, the line of distinction is not sharp; for 



instance, specimens of T. 2Klt(it(( occur in which the septa project far enough across the aperture 



as to make it almost an arbitrary matter whether they belong to the one species or to the other. 



The inadequacy of Dana's characters is also shown by a large specimen in the Collection wluch 



has all the characters of the calicles ascribed above to T. patula and which was so labelled by 



Briiggemann, but which has larger calicles than most T. peltata and a much thicker margin. 



On the other hand, as abovR stated, under this heading are grouped specimens which differ 



greatly from T. peltata, and it is they which, as it were, form the type of the species. It 



seems to me very probable that wlien our collections are more complete, the specimens now 



arranged under these two heads will have to be rearranged and further di\-ided. In this case 



Verrill's T. diehotoma, Ortmann's T. maxima, might be revived as good species founded upon 



the peculiar methods of growth. 



The large specimen from Sumatra, with tall, flat, narrow protuberances, belongs either 

 here or to the last species. As above stated (p. 39), I leave it here as it was so labelled by 



• Dana suggests that Ehrenberg's T. peltata is synonymous. But see footnote, p. 38. 



G 



