SYRINGOTHYRIS 391 



which is produced below in the free tube of the syrinx whose length is not 

 determined; muscular scars not well defined on the specimens studied. 



Brachial valve shallower than the pedicle, its greatest depth near the 

 front margin at the median line, the surface curving more abruptly to the 

 cardinal margin, somewhat compressed towards the cardinal extremities ; 

 mesial fold distinctly elevated to the beak, well defined, of moderate 

 height, rounded on top; the beak very short and but slightly projecting 

 beyond the cardinal margin; cardinal area linear; each lateral slope 

 marked by simple plications similar to those of the opposite valve but 

 somewhat stronger. 



The minute surface markings of the shell are not well shown upon 

 any of the specimens studied, but concentric lines of growth of variable 

 strength are usually present towards the front margin. Shell substance 

 punctate. 



Remarks. This species was considered as a synonym of S. extenuatus 

 by Schuchert in his discussion of the genus Syringothyris, 1 and "Winchell 

 evidently included specimens which must be identified as 8. extenuatus 

 in his S. lialli. The type specimens of the species, however, in the Univer- 

 sity of Michigan collection, are from bed No. 4, of the Kinderhook, at 

 Burlington, Iowa, and all of the specimens which have been observed by 

 the writer are from the same formation and locality. Specimens of 

 S. extenuatus in the University of Michigan collection were labeled by 

 Winchell as 8. halli var., showing that he recognized a difference between 

 them. The two species are entirely distinct, with no intermediate variations, 

 &nd can be easily distinguished. 8. halli is a sm'aller shell, less extended 

 along the hinge-line, proportionally longer from the beak of the pedicle 

 valve to the front margin as compared with the height of the cardinal 

 area, with a much more sharply defined mesial sinus towards the front 

 of the pedicle valve, with the transverse syrinx-bearing plate between 

 the dental lamellae, with a distinct median longitudinal ridge, and with 

 the angle between the cardinal area and the plane of the valve much 

 greater. The general proportions of the shell are more nearly those of 8. 

 hannibalensis, but it is a much smaller and proportionally shorter species 

 than that. 



Horizon. Kinderhook. 



SYRINGOTHYRIS BUSHBERGENSIS n. sp. 

 Plate LXXIII, Figs. 8-10 



Description. Shell above medium size, wider than long, the greatest 

 width near or on the hinge-line, the cardinal extremities rounded or sub- 

 rectangular. The dimensions of a large pedicle valve are: length from 



1 9th Ann. Rep. N. Y. State Geol., p. 33. (1890.) 



