1 66 NEW YORK STATE MUSEUM 



and indicating as we have said a progressed condition of one feature only. 

 Rensselaeria has many specific expressions and among the forms now referred 

 to it are several more significant departures than is presented by A m p h i- 

 genia elongata. 



Localities. Rensselaeria ovoides van gaspensis is very 

 common at Grande Greve at several localities and occurs also without vari- 

 ation except as indicated, in the Gaspe sandstones on the Portage road, 

 Gaspe Basin. At Perce the species is less common and often striking for its 

 great elongation of form. 



Rensselaeria sp. ? 



Plate 26, figures 6, 7 



There are a few specimens of Rensselaeria which differ from the 

 others in their very much coarser plication and in these the dorsal valve is 

 broadly and evenly flattened or depressed convex without the characteristic 

 median elevation of Renss. gaspensis. These are departures so wide 

 from the expression of the last named that they seem to indicate a distinct 

 form. The specimens are from Grande Greve. 



Beachia amplexa nov. 



Plate 26, figures 14-17 



Beachia suessana and Megalanteris ovalis Hall are two 

 very similar brachiopods in the Oriskany fauna. Whenever a considerable 

 number of specimens of both is available, those of the latter are, as Pro- 

 fessor Hall noted in 1859, generally larger, more compressed and propor- 

 tionally broader. Further differentials are found in the more broadly 

 rounded anterior margin of the latter, the absence of introverted margins 

 except at the cardinal shoulders and a low radial surface striation, coarser 

 but more obscure than in Beachia, and restricted to the marginal regions 

 rather than covering the entire shell as in that genus.' The critical distinc- 

 tion in the genera however is an internal one based on the structure of the 

 cardinal process. These features have been elaborately illustrated by Hall 

 & Clarke ^ whose figures show that in Beachia suessana this process 

 is distinctly rensselaeroid and consists of two flattened subtriangular plates 

 fused medially and thickened or cushion shaped at the sides with a median 

 foramen beneath the beak which is closed only by excessive calcification. 

 In M egalan tie ris ovalis this cardinal process is stout, subcylindrical, 

 doubly grooved at the extremity and rising from a flat hinge plate, as though 

 in effect the single cylindrical process were superinduced on the hinge plate 

 of a Beachia. 



'Billings's figure 471a of R e n s s. o v'a 1 i s given on page 962 of the Geology of 

 Canada^ is not that species but its size, form and surface striation indicate that it is the 

 form subsequently described by Hall & Clarke as R e n s s. c a y u g a. 



^Pal. N. Y. 1894. V. 8, pt 2, pi. 77, 



