ENVERTEBRATES. 135 



GASTEROPODA. 



GEMS PLEUROTOMARIA, Defrance. 

 PLEUROTOMARIA ILLI.NOIKNSIS. Wort-hen. 



PL XXIII, Figs. 6-6a-6b. 



Plenrotomaria illinoifnsis, Worthen, March. 1884. Bulletin No. 2, of the Illinois State 

 Museum of Natural History, p. 4. 



Shell disroiclal. s]>ire but slightly elevated; outer angle of the 



volution sharp, volutions about five, aperture ovate. 



Suture line marked by a row of small nodes, of which about ten 



may be counted on the last volution. A revolving slightly im- 



<1 baud may be seen with a good lens above the outer 



angle of the last volution, which probably joins the sinus in the 



lip: umbilicus shallow. 



This shell is most nearly related to the flat variety of P. 



sphferulatci, described by Prof. Cox, under the name of P. de- 



pirssn. but differs from that in its more flattened volutions, 



the impressed band on the lower volution, and its smaller and 



< onspicuous nodes. 



Breadth of an average size specimen 9 / 16 inch; height 3 / 16 

 inch. 



Position and locality: From a black limestone over one of 

 the lower coal seams in Mercer county. 111. 



Collector, A. H. Wort hen. 



No. 2530 of the Illinois State Museum. 



PLEUROTOMARIA GIFFORDI. Worthen. 



PL XXIH, Figs. 8-a. 



<nria giffordi, Worthen. March, 1884. Bulletin No. 2, of the Illinois State 

 Museum of Natural History, page 5. 



Shell small, conical, volutions about seven, spire sharply ele- 

 vated, the last volution forming less than half the entire length, 



