BRACHIOPODA. 91 



and breadth about equal. Ventral valve most convex at the umbo from which it slopes 

 regularly to the front and sides; sinus wide and very shallow or entirely obsolete, marked 

 by five or six plications; beak acute extended and slightly incurved. Dorsal valve very 

 slightly convex, beak incurved beneath the umbo of the opposite valve. Mesial fold 

 obsolete or represented by a very low broad elevation near the front, marked by five or 

 six plications. Surface covered by from 16 to 25 plications on each valve. These are 

 crossed by numerous fine concentric striae." 



Remarks — Only one specimen of this species has been collected during the present 

 investigation. It is slightly crushed but seems to differ in no respect from Kindle's 

 species though its occurrence so much higher in the geologic column is remarkable. 



Occurrence — Snyder Creek shale of Callaway County. 



Camarotoechia gregeri n. sp. 

 Plate 24, figures 5-9 



Description — Shell of medium size, subquadrate in outline, usually wider than long; 

 proportions of width to length 6-5 to 5-5. The dimensions of three specimens are: 

 Length 16 mm., 15 mm., 12 mm., breadth, 17 mm., 17 mm., 12 mm.; height 10 mm., 

 9 mm., 8 mm. 



Pedicle valve slightly convex; beak pointed and incurved; sinus of moderate depth, 

 originating slightly back of the middle and projecting prominently in front of the rest 

 of the valve. Three or four rounded plications occur in the sinus in most specimens, 

 one on each slope, and 6 or 7 on either side of the sinus. The total number of plications 

 ranges from 17 to 20. 



Brachial valve regularly convex from beak to front. The fold originates about the 

 middle and is sharply set off from the rest of the shell near the front. It forms part 

 of the regularly convex surface. There are four plications which occur on the top of the 

 fold, and usually, one on each flank. The usual number of plications on the valve is 18 

 and none of our specimens vary more than 2 from that number. 



This species resembles Camarotoechia contracta Hall but differs from it in the project- 

 ing fold, in having plications on the sides of the fold and sinus, and in the quadrate shape 

 with the top of the beak forming one angle of a rectangle. 



Greger 1 seems to identify the Snyder Creek specimens with Camarotcechia scitulus 

 Cleland, but that species has 24 plications, not including those on the fold and sinus, 

 while this species has only 14 or 16 at the most. 



Occurrence — Rare in the Snyder Creek shale of Callaway County. 



Genus Hypothyris King 



Hypothyris gregeri n. sp. 



Plate 17, figures 5-7, 11-14 



Description — Shell small, subglobose; width equal to the length in young forms, 

 greater than the length in old. Four specimens give the following measurements in 

 millimeters; 1 width, 2 length, 3 thickness. 11-9.5-8.7; 12.2-11, 9.5; 9-9-7; 9-9-7.3. 



In the pedicle valve the sinus affects only the front margin of the shell. It is shallow, 

 occupies more than half the width of the shell and is flat on the bottom. Beak pro- 

 jecting slightly back of the hingeline, not incurved. Plications rounded, simple, fairly 

 strong on the margin but become faint and obsolete about the middle of the shell; 

 four are present in the sinus and four on each lateral slope. The dental plates are short 

 and the median septum extends about 1/3 the length of the valve, as shown in figure 7 

 of plate 17. 



'Am. Jour. Sci., 49, p. 268. 



