194 NEW YORK STATE MUSEUM 



specimens are from Indian Cove and along the shore outcrops above and 

 below Fruing's, considerably above ^ the horizon of L. magnifica. 

 Billings's specimens were also from Grande Greve. 



Observations. The genetic relations of this species to L, magnifica 

 seem to be the following : In its various structural details, coarser plication, 

 . smaller muscle scars, usual absence of cardinal crenulations, smaller cardinal 

 denticulations and less pustulose interior all harmonize to indicate a more 

 primitive expression, or a form which when departing from the specific type 

 has maintained its primitive expression. L e p t o s t r o p h i a ma gn i f i c a 

 has traveled far from this prolific center of dispersion but of L. Irene we 

 know nothing except in this region. 



Leptostrophia oriskania Clarke 



Plate36, figures 7-18 



Leptostrophia oriskania Clarke. N. Y. State Mus. Mem. 3. 1900. p. 53, 

 pi. 7, fig. 29-35 , , , , ' 



Cf. S t r o p h o m e n a p e r p 1 an a Logan. Geology of Canada. 1863. p, 393; and 

 S. perplana Billings. Palaeozoic Fossils. 1874.. v,. 2, pt i, p. 3,2 



One of the most abundant brachiopods in the calcareous Oriskany of 

 Becraft mountain is a small perplane species with corrugated surface whose 

 general aspect suggests close affiliation with Lept. becki Hall of the 

 Helderberg limestone. The characters of this shell were thus defined by 

 the writer as cited: ' 



Shell of medium size, very gently concavo-convex. Hinge line-straight, attaining the 

 greatest width of the shell; at full growth very slightly produced at the, cardinal, extremi- 

 ties, but in young stages with quite decided extensions. Cardinal area narrow and mainly 

 confined to the pedicle valve; striated horizontally and crossed vertically by ridges which 

 make themselves apparent on the hinge line as denticulations. The area is .crossed .by a 

 ; narrow delthyrium which is generally covered. Surface of the pedicle valve covered with 

 fine, rounded striae which increase rapidly by intercalation. At intervals on the surface, 

 usually distant, are sharply defined concentric varices or growth' lines. Acc'Ohipanying 

 these are concentric corrugations, sometimes so pronounced and regular that the surface 

 suggests that of L ep t ae n a rhomboidalis, but generally finer and irregular. These 

 may extend over the entire surface or be best developed in the umbonal and median parts 

 of the shell; or they may be very obscure and often, when the concentric varices are fre- 

 quent and strong, may be altogether indistinct. Along the hinge line the wrinkles are 

 oblique, being parallel to the extended extremities of early -growth-stages. - ' < 



On the brachial valve the ornament is; of quite the same charaicter. The apophyses 

 and scars of the interior are those prevailing in this genus. The cardinal process is 

 bifurcated, and the posterior face of each division is concave. From the base of this proc- 

 ess diverge short, lateral ridges which are highly pustulose, between them lying a shorter 

 median ridge. In both valves the muscular scars are indistinct. ' - 



Di?nensio7is. Full grown shells seldom exceed a length -of 20 mm and a width of 

 25 mm. 



Shells with the above characters are quite freely distributed through 

 the upper layers of the Grande Greve limestones. There is no particular 



