HYDROZOIDS AND CORALS. 109 



much hesitancy in recognizing the species at all were it not for 

 the fact that good individuals were obtained at the typical 

 localities loug before the description of A. blairi appeared; 

 and consequently the form was already pretty well understood 

 when the diagnosis was published. Furthermore, it has been 

 deemed advisable, notwithstanding the somewhat doubtful 

 identity of the two forms, to adopt Miller's term, rather than 

 to propose a new name and place A. blairi among the spurious 

 species where it ordinarily would belong. This slender form 

 seems to be widely distributed geographically. 



Amplexus fragilis White & St John. 

 Amplexus fragilis White & St. John, 1867 : Trans. Chicago Acad. Sci., 



vol. I, p. 116. 

 Amplexus bicostatus Miller, 1891: Geol. Sur. Indiana, 17th Ann. Kept., 



p. 8, pi. i,fig. 10. 

 Amplexus coraloides { Many &,uthOT3 ; not Sowerby, 1814). 



Corallum simple, rather large, long, slender, cylindrical, 

 somewhat annulated, about two centimeters in diameter and 

 from 20 to 30 centimeters long; walls thin. Calyces moder- 

 ately deep ; lamellse but slightly developed, 32 to 40 in 

 number; transverse diaphragms numerous. Surface rather 

 distinctly marked by longitudinal lines. 



Horizon and localities. — Lower Carboniferous, Burlington 

 limestone: Sedalia, Louisiana; Keokuk limestone : Boonville; 

 Keokuk ( Iowa ). 



Zaphrentis acuta White & Whitfield. 



Plate xiil, fig. 4. 

 Zaphrentis acuta White & Whitfield, 1862: Jour. Boston Soe. Nat. Hist., 



vol V^III, p. 306. 

 Zaphrentis acuta Winchell, 1865: Proe. Acad. Nat. Sci., Phila., 111. 

 Zaphrentis parasitica Worthen, 1890 : Geol. Sur. Illinois, vol. V"1II, p. 79, pi. 



X, figs 5-5a. 



Corallum small, very robust, or subturbinate, slightly 

 curved, usually pointed at the base ; often bulging in the mid- 

 dle. Calyx oblique to the axis; moderately deep, with about 

 32 lamellae. 



Horizon and localities. — Lower Carboniferous, Kinderhook 

 limestone : Clarksville and Louisiana ( Pike county ). 



