50 EOCENE AND LOWER OLIGOCENE CORAL FAUNAS. 



i. e., thickeniug external to the calcification centers, throug-li the activity of 

 the inner face of the edge zone. 



I can not be sui'c that Ogilvie would have inclnded Dichocoenia in Her 

 AmphiastrseidsB, but she probably would have. Its structure is discussed 

 in considerable detail on page 140, in the descriptive ]iortion of this paper. 

 The wall is a typical pseudotheca. 



The following description of the wall of EuphijUid (/hihrcsceiis (Cha- 

 misso and Eysenhardt) is quoted from Bourne:^ 



The centers of calcification are present as conspicuous dark lines running down 

 the center of each septum. The primary and secondary septa are but slighly thick- 

 ened toward the peripheral ends, the tbeca being mainly composed of the heads of the 

 tertiary septa. Fig. 7 shows that in the upper part of the caylx the tertiary septa 

 project from a stouter thecal piece, the two together forming a T, of which the thecal 

 portion is the crosspiece. There are no sutures separating the septal from the thecal 

 portion. Lower down in the calyx the tertiary septa die out altogether, but the cross- 

 pieces re'presenting their thecal portions remain, and then the section has precisely 

 the appearance figured by Fowler in Lophohelia. From the relations which obtain in 

 Euphyllia, I am not disposed to think that the intercalated pieces figured by him are 

 essentially thecal structures sliarply distinguished from septa.'- 



An examination of the walls of a consideral)le number of genera of 

 the so-called Astra^idse has shown the same variability as in the above- 

 described Eusmilid genera; therefore it does not seem necessary to describe 

 the occurrence of eutheca and pseudotheca among them to get at a general 

 conclusion. 



Before stating such a conclusion T wish to note tlie character of the 

 wall iu Lophohelia proUfera (Pallas).^ This species possesses a true theca, 

 and has both ento- and ecto-crelic septa and tentacles, according to Fowler; 



lOp. cit., pp. 27, 28. 



-The following quotation from von Koch (Das Skelett der Stcinkoralk-n, ]t. 265) is apropos in 

 this connection: "In tier Sti'uktnr der Mauer findet sich ein Unterschicd, der wuhl iu dem Verhiilt- 

 niss der Septen zu den Parietes und der dadurch modlficirteu Ablagening von Verdicknngsschiehten 

 seine Erkliirung- findet: Komnien zwei Parietes auf eineu Intersept;ilraum so sind anf deni Qiier- 

 Bclinitt des Kelches zwischen je ^wei Septen zwei dunkle Trenuungslinieu zu bemerkeu. die ein 

 Manerstiick ein.sehliessen, das von keincm Septum durchkreuzt wird (sogenannte Eutheca), kommt 

 ahcr auf einen Interseptalrauni uur ein Paries, so findet sich zwischen zwei Septen uur eine Tren- 

 nungslinie, und die Mauerstiicke erscheinen nach der Lagerung der Krystallisationslinieu als 

 Anhlinge der Septen (sogenannte Pseudotheca [fig. 16]). Da das Einschieben ueuer Septen nicht 

 mit der \'ermehrung der Parietes glcichzeitig zu erfolgen braucbt, so kauu derselbe Kelch in einer 

 gewisseu Hc'lhe sich nach dein zweitcn.ja es kimnen sogar beideu Typen an demselben Querschnitt 

 vorkomnien (also Eutheca und Pseudotheca uelieneinander), wenu ein Thcil der Peripherie in seiner 

 Entwickcluug etwas vorgceilt oder nacligeblieben 1st (Taf. I, fig. 18). Die Theca kaun (lurch spiitere 

 Ablagerung, besouders ;iuf der ,\ussenseite, sebr verdickt werden (Taf I, fig. 21)." 



■'Fowler, Quart. .lour. Microsc. Sci., Vol. XXVIII, No. 109, Aug., 1SS7, |>i>. (i-10. 



