4O NEW YORK STATE MUSEUM 



less S. concinnus, quite uniformly varying however in the overarching 

 of the ventral cardinal area which brings the beaks into close apposition. 

 The preservation of these is such as to bring out more completely than 

 before known the precise character of the surface and furthermore the fact 

 that the surface of the ventral cardinal area when well retained shows the 

 peculiar twilled marking which has been observed on the exterior of shells 

 of Syringothyris. This sculpture is actually a series of extremely fine wavy 

 lines traversing the area obliquely subparallel to the margins of the del- 

 thyrium. It proves to be present on New York specimens also. When 

 Hall described this species he referred to an occasional specimen showing 

 indications of accessory plications on the anterior portion of fold and sinus. 

 Such a specimen was figured in volume 8, Palaeontology of New York, part 2. 

 This unusual and abnormal occurrence gives a veryfalse conception of the 

 relations of the species and has already been sufficiently misleading \pp. (itJ\. 

 Nothing of this sort has been observed in the Dalhousie shells and in the 

 New York shells only with the greatest rarity. It is well to note that 

 Spirifer concinnus is very closely approached by some of the shells 

 included by Schnur under the designation S. undiferus F. Roemer and 

 these Scupin has identified as S. gerolsteinensis Steininger [see 

 Palaontol. Abhandl. 1900, pi. 5, fig. 14]. 

 Horizon. Nos. i, 2, 8, 9, 10. 



Spirifer perlamellosus Hall 



Plate 8, figures 17-20 

 See pt i, p. no 



Spirifer perlamellosus Hall? Palaeontology of New York. 1859. 3: 201, pi. 26, 



fig. i, 2 

 Spirifer perlamellosus Hall & Clarke, op. cit. v. 8, pt 2, pi. 35, fig. 7-13 



This characteristic species of the Helderbergian fauna in New York is 

 well expressed in the Dalhousie beds. Correspondence in details of struc- 

 ture is shown throughout and specially pronounced in the latter is the 

 striation of the concentric lamellae. This feature carries no collateral 

 evidence of fimbriae though it may possibly imply such structure. This 

 evidence is in accordance with our observation made in the second of the 

 works above cited [p. i 7]. 



Horizon. Nos. 8, 9. 



Cyrtina chalazia Clarke 



Plate 7, figures 27-32 



Cyrtina chalazia Clarke. N. Y. State Mus. Bui. 107. 1907. p. 262 



We are presented in these shells with a departure from the usual aspect 

 of the Devonic Cyrtinas. They are mostly multiplicate shells and in the 

 early stages of this time conform quite generally to the same expression in 



