234 ANNALS NEW YORK ACADEMY OF SCIENCES 



overlapping the other. The surface is reticulate, but is also marked by 

 prominences and projecting lamellae. Only one species belongs to this 

 group, A. rugosus. A third type has the surface marked by relatively 

 very coarse, oblique, inosculating costte and has the two valves unequal, 

 but the left overlapping the right, just the reverse of typical Kirl-hya. 

 This group, Glyptophura, includes G. inopinata and G. angulata. 



I have not been able definitelv to ascertain to what familv it has been 

 the practice to refer the Kirkbyas, but I have the impression that they 

 ha've been considered as belonging to the Beyrichiidae. It seems to me a 

 question deserving careful consideration whether these shells do not 

 constitute an independent family, the Glyptopleuridse. Indeed, the dif- 

 ferences between Glypto pleura, on one hand, and Kirh'bya and Amphis- 

 ■sites, which are doubtless more closely allied to one another than to 

 Glyptophura, on the other, are such as to suggest that careful revision 

 might even prompt the erection of a third family, the Kirkb3'idas. 



Kirkbya lindahli var. arkansana var. nov. 



The general appearance and sculpture are like tbose of K. lindahli, though 

 the size is much smaller and the width proportionately greater. The shape 

 is subrhomboidal, narrowing slightly toward the front, and with a distinct 

 backward swing. The surface is finely checkered as in E. lindahli, and there 

 is a subcentral pit. The right valve overlaps the left on the free margins. 

 The double rim shown by Dr. E. O. 'Ulrich's figures seems to be lacking, and 

 the ventral border of the left valve is rather abruptly infolded for a short 

 distance toward the middle. Because of its smaller size, its lack of marginal 

 bands and its infolded margin, I am disposed to regard this as varietally dis- 

 tinct from K. lindahli. 



Kirkbya oblonga var. transversa var. nov. 



Our collection contains but a single specimen of this species, which is 

 so similar to the form which Dr. Ulrich identified as K. ohionga that I 

 am a little doubtful whether the varietal distinction here suggested is 

 altogether justifiable. The shape is strongly transverse, the dorsal border 

 being straight and extending very nearly the entire width. The ventral 

 border is nearly straight along the middle, more strongly rounded toward 

 the ends. One cardinal angle of our specimen is nearly quadrate, the 

 other is imperfect, but I believe was slightly extended. There is a well 

 marked flange separated from the ventral and lateral borders by a sulcus 

 and defined also upon its upper side by another sulcus. The remainder 

 of the shell is moderately convex, somewhat pinched together near the 

 middle \^ith a subcentral pit a little below the median line. The surface 

 is finely reticulated. 



