PLATE XIV 

 ONTOGENY AND PHYLOGENY OF THE TEREBRATELLID^E 



Figures represent brachial supports in various stages of growth in dif- 

 ferent genera and species. All are drawn of approximately the same 

 length to facilitate comparison, so that in general the younger stages are 

 much enlarged. Vertical rows of figures connected by dotted lines indi- 

 cate ontogeny as far as known. Horizontal rows indicate the same 

 growth-stages of higher forms and the adult structure in genera repre- 

 senting these stages. All figures are of recent species unless otherwise 

 stated. 



MORPHOGENY OF MEGATHYRIN^E (Page 300) 



FIGURE A. Early larval brachiopod without calcified brachial sup- 

 ports, but with circlet of centripetal tentacles on the lophophore. The 

 gwyniform stage. 



FIGURE Aa. Gwynia capsula Jeffreys ; a morphic equivalent of larval 

 stage, figure A. 



FIGURE B. Later immature stage of A ; showing growth of septum, 

 and consequent introversion of edge of lophophore. Early cistelliform 

 stage. 



FIGURE Ba. Zellania Hasina Moore, from the Lias; a morphic 

 equivalent of figure B. 



FIGURE Bi. Cistella neapolitana Scacchi ; showing calcification of 

 loop attached to septum, and other adult features. 



FIGURE 62. Megathyris decollata Chemnitz ; adult shell ; showing 

 advance over Cistella in the two lateral septa, thus increasing the length 

 of the loop. 



MORPHOGENY OF DALLININ^E (Pages 295-299) 

 Ontogeny of Macandrevia cranium Miiller 



FIGURE A. Gwyniform stage. 



FIGURE B. Cistelliform stage. 



FIGURE Ci. Platidiform stage ; showing union of descending lamellae 

 with dorsal septum. 



FIGURE Ci'. Side view of septum of preceding. 



FIGURE Di. More advanced platidiform stage ; showing growth of 

 ascending branches, or secondary loop. 



FIGURE Di'. Side view of same. 



FIGURE Ei. Ismeniform stage, with ascending branches still attached 

 to septum. 



FIGURE Fi. Miildfeldtiform stage; showing holes in ascending 

 lamellae as in Muhlfeldtia, figure Fa. 



