70 ' MADREPORAEIA. 



belong to one auother, coming all from the same locality (on the otlier hand, cf. Introduction, 

 p. 18) ; (2) some of them show unmistakable resemblance to T. hifrons ; (3) all of them seem 

 to form bifrontal folds early, the folds thus being small and narrow, whereas in T. consincua 

 the cup seems to grow to some size before the edge folds, and the fronds are large and deep. 



Many other interpretations of the phenomena presented by this curious little group of 

 specimens are possible, but until we have more and older specimens they must remain, like 

 that above put forward, purely speculative. 



Eehberg * describes, under this specific name, a large stalked, cup-shaped specimen from 

 the Tonga Islands, with broad folds fused back to back, the whole being 40 cm. across and 

 35 high. This, however, need not belong to this particular type of bifrontal Turbinarian. 

 It may belong to one of the following types. The depth of the living zone in T. hifrons is too 

 short to be developed from a cup, wliich, with its folds, reaches 35 cm. The fronds in the 

 subsequent growth of such a cup would almost certainly be deep, like those of T. conspicua. 



A fragment of an old stock. 



a. Locality unknown. [Register No. 53. 4. 8. 16.] (Type.) 



Group of young specimens from West Australia showing affinities both with T. hifrons 

 and with T. conspicua. 



h-g. West Australia. Purchased, Capt. Beckett. 



A minute specimen (86. 2. 26. 9.) 7 cm. in diameter, and showing an abnormal number 

 of twisted bifrontal folds. A great number of Ophiurids lurk in the crevices (PI. XXL, the 

 specimen on the right.) 



h. West Australia. Capt. Beckett. 



Species 54. Turbinaria conspicua. (PL XXIL ; PI. XXXIIL fig. 2.) 



Description. — Corallum develops from a cup, the folds of wliich fuse back to back, the 

 older coralla consisting of erect fronds with calicles on both sides ; the living zone on fronds 

 may be very deep, 15 cm. or more. 



Calicles never (?) projecting. On erect fronds the lower margin may stand out so that 

 the aperture looks upwards and outwards. Aperture oval, about 2 mm. longest diameter. 

 Septa 24, regular, often thick and granular, especially in young specimens, not reaching to the 

 half-radius circle, bending round from the margin to descend vertically round a large oval, 

 or slantingly round a funnel-shaped, fossa. The columella thus varies from a large, pro- 

 tuberant, oval mass, to a thin line of granules rising iip in the slit-like base of the funnel. 

 Transition stages can often be found on one and the same stock. 



The interseptal loculi are little more than notches between the thick septa. 



The coenenchyma is at the surface rough and granular, in section, usually very dense ; 

 without any marked development, at least in the older stocks, of a ridge-and-furrow system. 



It is impossible satisfactorily to divide up the many specimens which I have grouped 

 under this head, in spite of the great variations which they show in almost every point. 



*■ Abhandlungen aus dem Gebiete d. Naturwissensch. Hamburg, xii. (1892) p. 45. 



