80 MISSISSIPPIAN BRACHIOPODA 



by intercalation on the brachial valve, from 200 to 235 are present at 

 the distal margin of full grown shells, from 17 to 20 occupying the space 

 of three millimeters ; near the beak and towards the cardinal extremities 

 they become somewhat finer than in the middle part of the front of 

 the shell. 



Remarks. The specimens indicated as the types of this species in the 

 University of Michigan collection are eight in number, their horizon and 

 locality being marked "Chemung Group, Burlington, la." The so-called 

 Chemung Group at Burlington, of Winchell's time, is now included in 

 the Kinderhook, and to one familiar with the Burlington section the 

 several specimens may be recognized from their lithologic characters as 

 having come from more than one horizon in the Kinderhook, and perhaps 

 even from the base of the Burlington limestone. At least four of the 

 specimens are clearly from bed No. 7, the topmost bed of the Kinderhook 

 at Burlington, two examples, which may be specifically distinct, are from 

 the Chonopectus sandstone; one is from a white, granular chert which 

 may be from the Kinderhook oolite bed, but is more probably from the 

 Burlington limestone; and the last specimen is from the brownish, 

 crystalline limestone which is so characteristic of the lower Burling- 

 ton. The measurements given by "Wlnchell in his original definition 

 of the species, agree with those of the last specimen mentioned above 

 from the Lower Burlington limestone, and as this is in many respects 

 the most perfect individual of the lot it is believed to be the one from 

 which the greater part of the original definition was written. 



The species has been commonly confused with C. illinoisensis, but a 

 careful study of the original specimens seems to establish the species as 

 a good one. It grows to a larger size than C. illinoisensis and has more 

 angular cardinal extremities, the greater width of the shell usually 

 being along the hinge-line, while in C. illinoisensis the hinge-line is dis- 

 tinctly shorter than the greatest width and the cardinal extremities are 

 rounded. The radiating costag are also often somewhat finer than in 

 C. illinoisensis, although this distinction is not always to be depended 

 upon, since the more finely marked examples of C. illinoisensis are essen- 

 tially identical in this character with the more coarsely marked specimens 

 of C. multicosta; on the average, however, the costae of multicosta are 

 slightly finer than those of illinoisensis. In no specimen examined have 

 the cardinal spines been well preserved, and even the spine bases are 

 commonly very obscure, but there are clearly more than two or three, 

 as indicated by "Winchell, and there is apparently no basis for the state- 

 ment of that author that they extend at nearly right angles to the hinge- 

 line. 



Horizon. Upper Kinderhook and Burlington limestone. 



