134 



AR THR ODIRAN L UNG-FISHES 



have permitted the head to be thrown backward to a 

 degree which suggests the thoracic joint of an Elater. 

 On the ventral side of the trunk there occurs a flattened 

 plastron (Fig. 132) : its dermal -elements are connected by 

 overlapping margins ; they are lighter, and in some forms 

 (Fig. 135) lack the tuberculate surface of the dorsal 

 plates. Dorsal and ventral shields are connected by stout 

 lateral elements (Fig. 132, 7Z), which, passing ventrally, 



FIG. 135 



137 A 



Figs. 134-137. Dermal plates of Dinichthys. 134. Associated plates of head 

 and shoulders. 135. Plates of ventral armouring. (After A. A. WRIGHT). 136. 

 Pineal plate of Dinichthys intermedius, surface view. 137. Pineal plate of Dinich- 

 thys terrelli, visceral aspect. 137 A. Pineal plate, in sagittal section. 



ADL. Antero-dorso-lateral. A VL. Antero-ventro-lateral. A VM. Antero- 

 ventro-median. E. Ethmoid. EO. Epiotic. MO. Median occipital. PN. 

 Pineal. PO. Preorbital. PTO. Postorbital. PVL. Postero-ventro-lateral. SO. 

 Suborbital. X. External aperture, and -* , the axis of the pineal funnel. 



meet in the median line, and become the anterior support- 

 ing rim of the plastron. By some writers these have been 

 homologized as " clavicles." 



In further detail little is known of the anatomy of 



