256 NEW YORK STATE MUSEUM 



oblique plications which inosculate at their outer extremities along the 

 commissure. 



The hinge structure of this region shows analogy with that of Lunuli- 

 cardium in the following respects. There is an erect triangular area wholly 

 or nearly behind the beak ; at its posterior angle is a slightly projecting 

 process on one valve, which is probably recurved into a depression in the 

 other. Except for this departure the lower edge of the area is horizontal. 

 The divergent plications on the posterior crescent contribute to articula- 

 tion in the same manner as do the few coarse postumbonal ribs in 

 Lunulicardium. 



The surface markings may consist solely of simple ribs (H. simple x), 

 but in other species the plications are few in number, distant, and each 

 medially crested with a bladelike, vertical lamella ; one or two pairs of 

 smaller but erect lamellae may occur on the slopes of the major plications. 

 In some respects this genus resembles Mila Barrande,' but such similarity is 

 confined to the general form of the shells. Mila bears no hiatus, and no 

 clearly defined posterior crescent. 



The species of this genus are not now positively known outside of the 

 lower Upper Devonic of New York ; but it seems more than probable that 

 the shells described by Minister J as Cardium semialatu m, C. pauci- 

 costatum and C. alternans as well as C. triangulum Goldfs., 3 

 all from the upper Devonic of Elbersreuth, will prove to be Honeoyeas. 



Type, Honeoyea erinacea. 



Honeoyea erinacea sp. now 



Plate 6, fig. 15-22 



Shell small or of medium size, subtriangular. Beak posterior, crescent 

 rather short, concave and sharply defined ; sical margin longer, extending 

 for two thirds the length of the shell. 



Anterior slope vertical, posterior slope incurved. Surface sloping 



x Cf. M. deli cat a, Barr. Etage E : Syst. Sil. v. 6, pi. 244, fig. 8. 

 2 Beitr. 3 zur Petrefaktenkunde. 1840. p. 59, 60, pi. 13, fig. 1, 2, 5. 

 sPetref. Germaniae, pi. 142, fig. 3. 



