BRACHIOPODA. 383 



Anastrophla (?) hemlplicata, var. rotunda.] 



The generic position of Anastrophia ? hemiplicata and A. ? scqfieldi is left open 

 for the present until more is known of the interior of those Lower Silurian shells 

 with a camarelloid exterior. 



Formation and locality. Not uncommon in the upper part of the Galena shales eight to thirteen 

 miles south of Cannon Falls; and more rarely at Weisebachs' dam near Spring Valley, Fountain and Preston, 

 Minnesota; Decorah, Iowa; Neenah, Wisconsin. In the Trenton at Mifldleville, Watertown and Turin, 

 New York; Center county, Pennsylvania; Ottawa, Canada. 



Collectors. W. H. Scofleld, E. O. Ulrich and the writers. 

 Mus. Reg. Nos. 8232 to 8236. 



ANASTROPHIA? HEMIPLICATA, var. ROTUNDA, n. var. 



PLATE XXX, FIGS. 32-35. 



This variety is distinguished in having the length and width nearly equal, the 

 valves more convex and the plications somewhat more pronounced on the fold and 

 sinus, and less numerous on the lateral portions of the shell. The figured specimen 

 is strikingly distinct from typical A. ? hemiplicata in its greater convexity. Younger 

 specimens, however, are less pronounced in this respect, but are still distingished by 

 their shorter transverse diameter. 



Formation and locality. The specimen figured is from the middle portion of the Galena formation; 

 other smaller individuals have been secured from near the base of the same formation associated with 

 A. ? hemiplicta near Cannon Falls, Minnesota, and at Decorah, Iowa. 



Collectors. W. H. Scofleld and the writers. 

 Mus. Beg. No. 8231. 



ANASTROPHIA? SCOFIELDI, n. sp. 



PLATE XXX, FIGS. 24-28. 



This species seems to be a local development of A. ? hemiplicata, and differs 

 from it in having attained a larger growth, in being rounder in outline and in having 

 the valves less gibbous, while the smooth* or non-plicated portion of the shell is com- 

 paratively greater. The fold and sinus also are less marked features, while the number 

 of plications, not only here but on the lateral parts of the shell as well, is greater, 

 there being on the fold and on each side respectively five to seven and three to six 

 in A. ( ?) scofieldi to three to seven and three to four in A. ? hemiplicata. 



In the interior of the ventral valve there is a long, triangular and very narrow 

 spondylium, supported by a septum, and in the dorsal valve are the long crural plates 

 not unlike those in Anastrophia verneuili Hall.* When the shell is distorted so 

 that the posterior margins gape, it is seen that the dorsal valve has a very distinct 

 cardinal area, which is more conspicuous than that of the other valve. This feature 

 reminds one of species of Stricklandinia. 



Formation and locality. A cluster of thirty specimens was found by Mr. W. H. Scofleld near the 

 base of the Galena at a locality eight miles south of Cannon Falls, Minnesota. 



Mus. Reg. No. 8230. 

 Pal. N. Y., vol. ill, p. 260, pi. xi.vin, fig. 1. 



