106 HYDROZOIDS AND C0R4LS. 



Surface marked by numerous fine, annular wrinkles of growth, 

 which pass around on the broad folds as well as the interven- 

 ing constrictions; vertical striations poorly defined. 



Horizon and locality. — Lower Carboniferous, Upper Kin- 

 derhook (Chouteau) limestone: Ciirryville (Pike county). 



This species bears considerable resemblance to C. corni- 

 cula (Ed. & H.) from the Devonian, but it has a more slender 

 form, a very deep calycinal cavity, much more numerous and 

 delicate lamellae^ while the surface is perfectly smooth and is 

 more annulated. There is some doubt as to the correctness of 

 the generic reference of this form, as it possesses many of 

 the characteristics of Campophyllum ; especially as the lamellae 

 are rather short, and do not appear to meet in the center, 

 except, perhaps, in the immediate vicinity of the base. This 

 apparent blending of the structural features found in two 

 different genera is quite suggestive when taken into consider- 

 ation with the commonly recognized geological range of the 

 corals of this group. True forms of Cyathophyllum are dis- 

 tributed most widely in the Silurian and Devonian; while 

 Campophyllum is most abundant in the later Devonian and the 

 Carboniferous. In America the first of these genera is almost 

 entirely confined to strata earlier than the Carboniferous. 

 The forms of the second group, with a single exception, belong 

 to the later Paleozoic. 



Lithostrotion mam i Hare Castelnau. 



Plate xii, fig. 8. 



Astrce mamillaris Castelnau, 1843 : Terraine Sil. de I'Amerique du 

 Nord, p. 50, pi. sxiv, fig. 5. 



Lithostrotion mamillare Edwards and Haime, 1841 : Monog. des Polyp., 

 p. 433. pi. XIII, figs. 1-lb. 



Lithostrotion basaliiforme Owen, 1852: Geol. Wisconsin, Iowa and 

 Minnesota, tab, iv, figs. 5 and 6 



Lithostrotion mamillare Hall, 1858: Geol. lowa, vol. 1, p. 667, pi. xxiv, 

 figs. 5a-b. 



Lithostrotion proliferum Hall, 1858 : Geol. Iowa, vol. I, p. 668, pi. xxiv, 

 figs. 6a-c. 



Lithostrotion mamillare Rominger, 1876 : Geol. Sur. Michigan, vol. Ill, 

 p. Ill, pi. Iv, figs. 1-2. 



