312 HTDROZOIDS AND CORALS. 



with the septal fossette prominent; lamellae well defined, about 

 40 in number in the average mature individuals. Epithecal 

 crust smooth, rarely wrinkled. 



Horizon and localities. — Lower Carboniferous, Burlington 

 limestone: Louisiana; Kinderhook (Illinois); Bonaparte 

 (Iowa). 



Zaphrentis chouteauensis Miller. 



Zaphrentis chouteauensis Miller, 1891: Geol. Sur. Indiana, 17th Ann. 

 Kept., adv. sheets, p. 8, pi. i, figs. 11-12. 



Somewhat like Z. calceola, with the calyx very oblique to 

 the axis of the corallum. 



Horizon and localities. — Lower Carboniferous, Kinder- 

 hook (Chouteau) limestone : Sedalia. 



Zaphrentis exigua Miller. 



Zaphrentis exigua Miller, 1891 : Geol. Sur. Indiana, 17th Ann. Rep , adv. 

 sheets, p. 11, pi. i, figs. 19-20. 



This form is characterized by its minute size, attenuated 

 base and rapidly expanding corallum. 



Horizon and localities. — Lower Carboniferous, Chouteau 

 limestone: Sedalia. 



Zaphrentis centralis Worthen. 



Zaphrentis centralis Worthen, 1890 : Geol. Sur. Illinois, vol. VIII, p. 72, 

 pi. ix, figs. 1-la ; and pi. x, figs. 13-13a. 



A large, rather robust form like Z. dalei, but with fewer 

 lamelliTe and apparently no indications of spines on the outer 

 surface. 



Horizon and localities. — Lower Carboniferous, Burlington 

 limestone : Louisiana, Hannibal, Helton ( Marion county ), Ash 

 Grove, Springfield, Sedalia, Ste. Genevieve; Keokuk lime- 

 stone: La Grange, St. Francisville (Clark county); Keokuk 

 and Bonaparte ( Iowa) ; Warsaw (Illinois ). 



Although Worthen's diagnosis of this form is very un- 

 satisfactory, it is quite evident that he had in hand the widely 

 distributed type so common throughout the Burlington and 

 Keokuk rocks of the states of Missouri, Iowa and Illinois. The 

 species appears to be especially abundant ia the Burlington 



