Cretaceous Species of Podoseris, Dunc. 39 
genera which have the synapticule without any junction- 
lines, and they blend without lines of union. These are 
true (echte) synapticule. Pratz, following Milaschewitsch, 
gave some excellent figures of the kinds of synapticule (op. 
cu. pl. ix. figs, 7d, 12a, 13a, and 14a), and quoted his 
predecessor’s remark that it is necessary to distinguish be- 
tween the kinds of synapticule in classification. All the 
descriptions of these authors are excellent, and nothing can be 
more true than Pratz’s delineations; but, as was shown after 
the publication of their essays, the modern example fails to 
substantiate the value of the distinctions between the kinds 
of synapticule (Duncan, 1884, Journ. Linn. Soc., Zool. 
vol. xvi. p. 146), and, moreover, the microscopic investiga- 
tion of Siderastrea and of a true Tertiary Thamnastrean 
leads to the same result as the study of Mungia; that is to 
say, as both kinds of synapticulz are found in the same speci- 
men of a species, and the difference between the kinds of 
structures is of no physiological importance, the distinction 
between so-called true and false synapticulee is of no classifi- 
catory value. 
The synapticule in Podoseris are therefore both thick and 
thin, long and short, and are long from without inwards and 
obliquely placed upon the flanks of opposed septa, which they 
unite. Thislast kindisa feeble representative of the sy napticulze 
of the recent Fungia, and as in that genus the upper and the 
lower synapticule form the roofs and bases of so many oblique 
canals in regular succession. ‘The delicate dissepiments inter- 
fere with the continuity of the lumen of the canals. 
The Epitheca.—This structure varies in amount according 
to the height of the corallum. When the coral is low and 
plano-convex the epitheca is scanty or absent, and it exists 
over more or less of the coste close to the periphery. But 
when the coral is tall the cylindrical or nipped-in stem above 
the attached base is covered with epitheca up to varying 
heights, but usually to the calicular margin. ‘The epitheca is 
thin, moulded as it were to the outer edges of the coste and 
to their interspaces; it is more or less granular, and it must 
have prevented any watery connexion between the synap- 
ticular canals and the surrounding medium. 
There is no epitheca on the attached base, but the lower 
surfaces of the septo-coste are in contact with the foreign 
body supporting the coral, and the synapticulee may be seen 
to exist between the septa in concentric rows. ‘The coral 
appears never to have been free. 
in the very interesting young form the low septa and twe 
concentric series of synapticule form all the coral. 
a 
