SOME NEW BRACHIOPODS AND GASTROPODS 221 



specimen that I have selected for the type of this mutant. In the 

 holotype the sinus and mesial fold are very prominently developed, 

 the beak of the ventral valve is quite strongly curved, and the 

 specimen somewhat damaged. The real distinguishing point of 

 this form is its mucronate character of growth, which is very charac- 

 teristic. 



Holotype: — Number 451, collection of C. L. Fenton. Spirifer 

 zone, pits of Rockford Brick and Tile Company, Rockford, Iowa. 



In this same connection I think it advisable to republish the 

 description of a new genus and species of gasteropod, described by 

 Clement L. Webster on pages 39 and 40 of Volume I of the " Iowa 

 Naturalist" (April, 1905). 



Floydia Nov. Gen. 1 



"Shell large and thick; spire high, or low with volutions partially 

 enrolled upon themselves; volutions rounded, inflated, or somewhat 

 angular or flattened on the side, especially the body volution; 

 volutions four to six; suture strong and deep. Aparture large, gen- 

 erally subcircular to subovate; umbilucis closed; inner or columella 

 lip much thickened and generally flattened; outer lip usually simple. 

 The upper one-fourth to one-half of the first, and generally the 

 second, volution marked by regular, heavy folds, which arch ob- 

 liquely back and then forward from the suture. Surface of the 

 volutions usually marked by transversely oblique, more or less 

 strong striae of wrinkles of growth. 



' ' The description of this genus is based upon the species Floydia 

 concentrica of this paper 



Floydia concentrica nov. spec. 



"This species has been quite fully described in delineating the 

 genus. 



"The shell varies somewhat both in the young and adult form. 

 In the young stage the heavy folds are present only on the upper 

 portion of the body volutions ; the upper surface of the body volu- 

 tions in the low spire variety is sometimes much flattened; the 

 form of the first whorl in the young stage varies somewhat in 



1 This genus was originally described as "Floyda." This was, however, 

 incorrect, and the spelling "Floydia" is here used with Webster's approval. 



