176 GrASTEROPODS. 



tudinal series of long tubular spines, extending from the aper 

 tural margin about three fourths the distance to the apex. Of 

 these spiniferous rows two are disposed laterally, one on each 

 side and the third centrally and dorsally. 



Horizon and localities. Lower Carboniferous, Burlington 

 limestone: Hannibal, Louisiana. 



This is one of the few spiniferous species belonging to the 

 genus Oapulus ; and only two others of similar character occur 

 in the American Carboniferous rocks. It appears to be closely 

 allied to C. biserialis ( Hall ), and may eventually prove identi- 

 cal with that form, from which it apparently differs only in 

 having three, instead of two, rows of spines. Thus far it has 

 been noted only in the two divisions of the Burlington lime- 

 stone, when it occurs in the thin sandy-clay partings, associated 

 with delicate and beautifully preserved bryozoans. The type 

 specimen is not a characteristic representative of the species, 

 being in several particulars quite abnormal. 



Capulus latus (KEYES). 



Plate liii, figs. 13a-b. 



Platyceras latum Keyes, 1888: Proc. Am. Philosophical Soc. , vol. XXV,. 



p. 242, figs. 10-11. (Reprint, p. 14.) 



Platyceras latum Keyes, 1889: Proc. Acad. Nat. Set., Phlla., p. 290. 

 Capulus latus Keyes, 1890: Am. Geologist, vol. VI, p. 9. 

 Platyceras latum Miller, 1890 : N . A. Geol. and Pal. , p. 416. 

 Capulus latus Keyes, 1890: Proc. Acad. Nat. Sci., Phila., p. 168. 



Shell somewhat like C. equilateralis in general physiognomy, 

 but more campanulate, and with the apical parts relatively 

 smaller. 



Horizon and localities. Lower Carboniferous, Burling- 

 ton limestone: Burlington (Iowa); Hannibal. 



This form is seldom well preserved, the majority of the 

 specimens being more or less exfoliated. 



