260 PALAEONTOLOGY OF NEW YORK. 



entfernt sich aber durch das grosse Dorsal septum und die Ueberdeckung der 

 StielofFnung doch so sehr von denselben, das ich es nicht gewagt habe, die 

 Form jener Reihe einzufiigen. Beide genannten Charaktere entfernen unsere 

 Art von den echten Orthis-Arten iiberhaupt, und der letztere, das Pseudodelti- 

 dium auf der Ventral area, spricht fiir ihre Stellung bei Strepiorhynchus. Doch 

 hat der echte Strepiorhynchus ein Pseudodeltidium auch auf der Dorsal area, 

 welches ich bei lepidus vergeblich gesucht habe." 



\;. 

 \ Figs. 15, I(J, 17. Strept,orhyvdi'i/s7 lepidua, Afler Kay.skr. 



Though represented by only a single known species the form is an important 

 one in the series of streptorhynchoid genera and it is therefore separated under 

 the name above proposed.* 



Diagnosis.! Shell subsemicircular ; hinge-line nearly equaling in length the 

 greatest width of the shell ; convexity normal. Pedicle-valve more convex 

 than the brachial ; area moderately high ; delthyrium covered by a convex 

 plate. Brachial valve slightly convex ; area narrow ; delthyrium covered. 

 In the interior, a large, triangular median septum extends almost to the bot- 

 tom of the opposite valve. Surface with a slight median ridge and furrow 

 on brachial and pedicle-valves respectively ; covered with sharp plications, 

 increasing by intercalation near the margin. 



Shell-substance punctate. 



Type, Orthis lepida, Schnur. A somewhat rare species in the " Crinoiden- 

 schichten" of the Middle Devonian at Pelm and Gerolstein. 



* The publication of tliis generic description in the present volume has received the approval of Pro- 

 fessor Kayser, and the name proposed is in recognition of the eminent services of that author in Geological 

 and Palseontological Science. 



t Deiived from Kayser's description of the type-species. 



