TURBINARI^ BIFRONTALES. 71 



The following variations may be specially noted. 



1. Whereas some stocks have but few erect fronds, with great depths of living coral, other 

 stocks are composed of a mass of closely gyrating fronds showing only a very narrow li\'ing 

 zone (5 to 6 cm.). In these cases, the narrowness of the living zone is clearly due to the 

 crowding of the fronds ; this is shown by its much greater depth wherever, on the same stock, 

 the fronds are more exposed. 



2. The suture along the edges of the fronds is very variously developed. A slight ridge 

 separating the young calicles of the one face from those of the other is almost always to be 

 seen. In others, again, this ridge is ■widened, and here and there shows traces of a median 

 trough. This trough may, again, widen and deepen as if the fused folds were about to separate 

 again. 



3. The erect fronds may break up into finger-shaped processes, which give the whole stock 

 an appearance but little resembling that of the type. 



•4. In addition to these, there are the differences in the calicles mentioned above, the small 

 funnel-shaped fossiB being very frequent on erect fronds when the calicles look upwards, while 

 the calicles with the large oval fosste and conspicuous columellie are very frequent in younger 

 cup-shaped specimens. 



5. Again, while tlie granular character of the ccenenchyma is marked on the erect fronds, 

 in the young cups the flow of nutritive matter downwards towards the base and stalk is 

 indicated by a marked ridge-and-furrow system. 



Had there been only a few specimens showing the variations above described, they would 

 almost certainly have been classified under so many different specific names. 



The question may then be asked, why separate this from T. hifrons ? The main distinction 

 between the two (which I wish to emphasise by separating them) lies in the great depth of the 

 living frond in the latter, and its narrowness in the former. 



The National Collection fortunately possesses a great number of specimens of this mag- 

 nificent coral, almost all collected by Mr. SaviUe-Kent in Shark's Bay. They show all stages 

 of growth, from the minute cup but a few cm. across, to gigantic bushes of erect fronds 3 feet 

 liigh, and many feet round. 



These upright fronds show the phenomenon which at first led me to believe in successive 

 periods of growth ; the real explanation of the sharp contrasts between the lining and dead 

 portions being found in the downward streamings of the ccenenchyma. (See Introd., p. 12.) 



The colour of the stocks before bleaching appears to have been dark brown. 



Old stocks of large size. 



a-e. Shark's Bay. SaviUe-Kent Coll. 



Of these, the specimen registered 94. 3. 9. 4. is specially worthy of note because two 

 varieties, one with large columella and one with small, are growing side by side without 

 fusing. They are in conjunction with T. maijna. The whole group of three specimens 

 further illustrates the striking likeness so often noted between corals of different species 

 when coming from the same locality. 



/. Shark's Bay (also with T. magna). Saville-Kent Coll. [Register Xo. 94. 3. 9. 7.] 



g-l. Shark's Bay. Saville-Keut Coll. 



m. Shark's Bay. Saville-Keut Coll. 



