310 Systematic Paleontology 



Three closely related fonns have been described, F. niarjarensis Hall 

 from the Lockport limestone, F. helderhergiw Hall from the Coeymans of 

 New York, F. helderhergia; var. prwcedens Schuchert from the Cobleskill 

 of New York. It seems probable that they are but one species. Hall com- 

 ments upon the similarity of F. lielderhergm to F. niagarensis and states 

 that the latter differs in having more niunerous diapliragms and in having 

 the mural pores on the lateral faces instead of near the angles of the cells. 

 As Lanibe,' however, states, Hall's figures of F. niagarensis show that the 

 distance of tabulae is very variable while he illustrates its mural pores in 

 the same position as in F. lielderhergiiv. The difference, therefore, re- 

 solves itself into the more irregular shape of corallum, somewhat greater 

 average distance of tabulae and difference of stratigraphic horizon. Of 

 these the manner of growth would appear the chief difference, the 

 specific value of which may be questioned. 



Schuchert^ has established F. helderhergim var. prcecedens for the 

 irregularly shaped specimens from the Cobleskill of New York which 

 agree in other respects with F. helderhcrgicp. He says: " F. niagarensis 

 is usually small and spheroidal or irregular in form in the Eochester shale, 

 while F. lielderbergia' of the Coeymans limestone is often in large, lentic- 

 ular, depressed convex or hemispherical masses. The Cobleskill speci- 

 mens are spheroidal to lenticular colonies up to six or eight inches in 

 diameter, and the other characters are also those of F. helderhergice, 

 and not of F. niagarensis. Since the Cobleskill specimens never attain 

 the size of the largest F. helderhergia; (sometimes having a diameter of 

 two feet in Albany County) to which they are related, it seems inadvisable 

 to retain longer Hall's provisional identification. It may l)e known as 

 F. lielderhergia pra'cedens.'" 



The variety described by Schuchert seems identical in all essential 

 respects witli F. niagarensis Hall, except in the lesser average distance of 

 its tabu];ie, a very variable feature in this genus. This is the most common 

 species of this genus in the Helderberg of Maryland, being very profuse in 

 the upper Stromatopora beds of the Keyser member, wherever exposed. 



' Contributions to Canadian PaL, Revision Paleozoic Corals, vol. iv, 1889, pt. i, 

 p. 7. 



- Amer. Geol., vol. xxxi, 1903, p. 164. 



