388 MISSISSIPPIAN BRACHIOPODA 



plications similar in number to those of the opposite valve but somewhat 

 stronger. Internally the cardinal process is broad and concave towards 

 the front, on the floor of the valve a slight median ridge extends anter- 

 iorly from the cardinal process for about one-third the length of the 

 valve ; the muscular scars not well defined. 



The minute surface markings are not shown upon the exfoliated speci- 

 mens available for study, but the shell substance is minutely and closely 

 punctate, the punctee are well developed not only upon the body of the 

 shell but also upon the cardinal area except in the vertically marked, 

 differentiated region lying on either side of the delthyrium. 



Remarks. This species was originally described from a brachial valve 

 only, but more recent collections from the Chonopectus sandstone and the 

 superjacent bed at Burlington, Iowa, have afforded an abundance of 

 material which shows all of the essential characters of the species. It is 

 a well-marked species characterized by its acutely angular cardinal ex- 

 tremities, the shortness of the pedicle valve from the beak to the anterior 

 margin, this distance being shorter than or at least no longer than the 

 height of the cardinal area, and by the small angle between the cardinal 

 area and the plane of the valve. The species is not a large one, although 

 it sometimes attains a somewhat greater size than the dimensions given, 

 the largest specimen observed, a brachial valve, having a width of 64 mm. 

 along the hinge-line. Occasional examples are slightly distorted or 

 twisted towards the beak of the pedicle valve. 



Horizon. Chonopectus sandstone of the Kinderhook. 



SYRINGOTHYRIS HANNIBALENSIS (Swallow) 

 Plate LXVIII, Figs. 1-7 



1860. Spirifer (Cyrtia?) Hannibalensis Swallow, Trans. St. Louis Acad. 



Sci., vol. 1, p. 647. 

 1890. Syringothyris Carteri Schuchert, 9th Ann. Rep. N. Y State Geol., 



p. 30 (in part). 

 1895. Syringothyris Hannibalensis Hall and Clarke, Pal. N. Y., vol. 8, 



pt. 2, pi. 25, figs. 33-35. 

 1908. Syringothyris hannibalensis Rowley, Mo. Bureau Geol. and Mines, 



vol. 8, 2nd ser., p. 82, pi. 18, figs. 6-9; p. 88, pi. 19, figs. 4-5. 



Description. Shell rather large, much wider than long, the greatest 

 width near the hinge-line, the cardinal extremities narrowly rounded. 

 The dimensions of a nearly complete, exfoliated specimen are : length of 

 pedicle valve from beak to front 30.5 mm., length of brachial valve 

 25.4 mm., width 51.5 mm., length of hinge-line 48 mm., height of cardinal 

 area 16.3 mm., thickness 28 mm., width of sinus in front 17 mm., width 

 of delthyrium at base 11.6 mm. 



Pedicle valve subpyramidal in form, the surface sloping from the 

 umbonal region to the cardinal extremities in nearly straight lines which 



