STREPTORHYNCHUS. 



29 



Family— STROPHOMENID^E. 



Sub-genus — Streptorhynchus, King} 



In 1853 I was tempted to suppose Professor King's genus Streptorhynchus 

 synonymous of Orthesina, D'Orbigny, but the perfect interiors, which I have recently 

 studied, have led me to abandon that view, and to consider both to be characterised by 

 certain well-defined peculiarities, which will be better understood by the comparison of the 

 subjoined illustrations. 



Fig. l. 



Fig. 3. 



Fig. 2. 



Streptorhynchus Devonicus, D'Orbigny, species. 

 Fig. 1. Both valves, seen from the beaks. Fig. 2. Interior of the larger or ventral valve, as seen 



under the area. Fig. 3. Interior of the smaller or dorsal valve. 



Fig. 4 



Orthesina anomala, Schlotheim, species. 



Fig. 4. Both valves, seen from the beaks. Fig. 5. Interior of larger or ventral valve, seen under the 

 area. Fig. 6. Interior of the smaller or dorsal valve, a. Adductor scar. d. A deltidium of the 

 smaller valve, f. Foramenal aperture, under side of deltidium. j. Cardinal process, m. Cavity on 

 either side of the mesial septum, n. Dental plates, o. Horizontal plate, supported by a septum. 

 r. Cardinal muscular impressions, s. Sockets, t. Teeth, v. Vascular impressions. 



A 'Monograph of English Permian Fossils,' Palaeontog. Soc, p. 109, 1850. Etym. o-peirtw, I bend 

 or twist, and pvyyos, a beak. 



