32 BULLETIN OF THE LABORATORIES 



extremely arcuate, the beak recurved upon itself so that the hinge line 

 is nearly opposite the centre of the back of the shell ; hinge line shorter 

 than the width of the shell ; cardinal extremities produced mto small 

 angular ears. Surface marked by strong radiating costae, which bifur- 

 cate upon the umbo and below, and sometimes coalesce toward the 

 base of the shell ; entire surface covered by fine undulating concentric 

 striae, and, in the upper part, a (ew strong wTinkles, which are con- 

 spicuous on the ears and umbo. A few marks of the bases of spines 

 are noticed, but they appear to have been irregularly distributed." 



This species is P. semireticulatus in miniature. Our specimens 

 differ from Hall's figures chiefly in the greater irregularity of the striae, 

 in this respect, however, agreeing with his description. 



Length 17 mm; width about 15 mm; hinge 14 mm. Near congl. 

 II, Granville and Newark. 



Prodwctus flemin^i, vav. hiirHn^tonensis. H. 

 (Plate III, Fig. 20 [and 22?]) 



A few specimens, apparently from the upper division of the Wa- 

 verly, resemble very closely this species. The occurrence of a Bur- 

 lington species in this horizon is certainly suggestive. 



Proditctus {Product ell a) shinnardianus , H. 



Plate VII, Fig. 18; Plate VI, Fig 16?) 



(= Productus subaculeatus, Murch.) 



Prodiictus subaculeatus, has been identified by Hall, from the Cor- 

 niferous He says : 



" I have been unable to identify it with any species in the Ham- 

 ilton and Chemung groups of New York, though the resembling those 

 which I have placed under P. shumardiana. i\ larger collection of 

 specimens may possibly show a passage from one to the other." 



Productus shumardianus is doubtless identical with P. spiniilicos- 

 ius, H., P. CO nee ?j trie us, H: and P. pyxidata, H., while P. lachry?nosa 

 is perhaps less closely allied, though a member of the same series. 



