DESCRIPTION OF SPECIES— ANTHOZOA 277 



Remarks. — This species was originally described as a variety of P. 

 enorme, the type specimen being recorded as coming from "Salt Lick 

 Point, Monroe county, Illinois." This locality is in the Mississippi 

 Eiver bluffs opposite Yalmeyer and is one of those points where the Fern 

 Glen formation is typically developed. It is possible that this form and 

 P. enorme are only variations of a single species ; but if that be the case, 

 the form to which the name depressus has been applied is the normal 

 form in the Fern Glen fauna at least. It occurs at all the principal Fern 

 Glen localities, and scores of individuals have been observed, but no exam- 

 ples with the characters of the typical P. enorme have been seen associated 

 with them. The form here described as P. biftdus is more nearly like 

 the typical form of P. enorme, but even this seems to be specifically dis- 

 tinct. 



There seems to be no valid reason for considering this little fossil as a 

 sponge, as was done by Meek and Worthen. In their present condition 

 of preservation the specimens are entirely similar to the associated un- 

 doubted corals, and therefore the original substance of the organism must 

 have been the same, namely, calcium carbonate. If it was a sponge, it 

 certainly was not a siliceous sponge. It seems altogether more probable 

 that the creature was a coral of peculiar type. In its coralline relation- 

 ships, however, the form seems to be unique, but perhaps no more so than 

 the coralline forms of the genus Monilopora. 



PAL/EACIS BJFIDUS n. sp. 

 Plate 10, figures 8-11 



Description. — Corallum cuneate at the base, two-celled, with the aper- 

 tures divergent. The structure of the corallum and surface markings 

 are as in P. depressus. 



The dimensions of a large example are: Length, 13.5 millimeters; 

 width, 6.5 millimeters; height, 11 millimeters; maximum diameter of 

 corallites at aperture, 7 millimeters. 



Remarks. — This form is much more rarely met with in the Fern Glen 

 fauna than P. depressus, from which it is quite distinct by reason of its 

 distinctly wedge-shaped form. Furthermore, no distinctly intermediate 

 examples connecting the two forms have been observed. The species 

 perhaps more closely approaches P. enorme in its general characters than 

 it does P. depressus, but it differs from that species in the smaller num- 

 ber of corallites and in the more distinctly cuneate form of the corallum. 

 In none of the individuals observed are there more than two cells, 

 although it is possible that examples may be met with which will have a 

 larger number. 



