Vol. G^T] MR. S. S. BTTCKMAN ON BRACHIOPOD MORPHOLOGY. 343 



EXPLANATION OF PLATE XXIV. 



Table of Developmental Stages op Test. 



[The Table is not intended to indicate genetic series, or geological sequence, 

 only sequences of develop mental phases of test-ornament, in the one case subse- 

 quent to Cincta, in the other case prior to Eudesia. All the figures are of the 

 natural size, except where otherwise stated.] 



Lenticular Stage. 

 Fig. 1. Cincta orbicularis (Ziet.) after Zieten {Terebratula orbicularis). 



Carination opposite. 

 Cincta-St&ge. 

 Fig. 2. Cincta per nummus, nom.nov., after Deslongcharnps {Terebratula numis- 

 malis). 



Quadrifid Stage. 



Fig. 3. Zeilleria subquadrifida (Oppel). 



4. Zeilleria quadrifida (Val.). 4 a = dorsal and 4 6 = ventral views, to 



show opposition of carinas. 



5. Zeilleria cf. quadrifida (Val.). 



[Figs. 3-5 after Deslongchamps {Terebratula quadrifida).'] 



Quadricarinate Stage. 



Fig. 6. Trigonella Fleuriausa (d'Orbigny), after Quenstedt {Terebratula 

 trigonella). 



Multi cari nattr Stage. 



Fig. 7. Trigonellina pectuncidus (Schloth.), after Quenstedt ( Terebratula pectun- 

 culus). 



Carination alternate. 

 TJniplicate Stage. 



Fig. 8. Terebratula Whitakeri, Dav., after Davidson. 8 a, dorsal view ; 

 8 b, anterior view, showing uniplication. 



Unicarinate Stage. 

 Eig. 9. Ismenia Murckisonce, Desl., after Deslongchamps's enlarged figure. 



Quinquecarinate Stage. 



Fig. 10. Ismenia Munieri (Desl.), after Deslongchamps's enlarged figure 

 {Megerlea Munieri). 

 11. Ismenia pectunculoides (Schlotheim), after Quenstedt {Terebratula 

 pectunculoides). 



Multicarinate Stage. 



Fig. 12. Flabellothyris flabellum (Defrance), alter Davidson's enlarged figure 

 ( Terebratula flabellum). 

 13. Eudesia orbicularis (Sowerby), after Davidson {Terebratula cardiwm). 



