New Species of Devonian Fossils. 119 



for P. lenticulare, excepting' that the earlier and ancestral spe- 

 cies, P. trifoliatum, attains maturity at the three-celled stage and 

 usually does not proceed further. The specimen with the initial 

 zooid only is especially instructive, since it was not attached to 

 any solid support and the basal side is therefore free to observa- 

 tion. The corallite appears to be mature, though the lateral buds 

 failed to develop. It is at least suggestive that the lack of the 

 usual solid support for the colony was the reason for this. The 

 places where the buds should have developed are indicated by 

 nodes on the outside of the corallite, and by corresponding pits 

 within. As is to be expected, one of them appeared earlier than 

 the other. Figure 5 of Plate I is also interesting, since the 

 lateral corallites have not covered the prostrate initial portion 

 of the primary corallite. The development of the typical tri- 

 foliate corallum took place in the following manner : The initial 

 cell was at first procumbent, spreading rapidly and secreting an 

 attached base. When this base had been completed, the upward 

 groAvth of the walls began. At this point a lateral cell budded 

 off from one side of the initial corallite, and soon thereafter a 

 second one budded off from the opposite side. These secondary 

 cells spread their procumbent bases, often covering the prostrate 

 apex of the parent cell, and then as they grew upright, developed, 

 with the initial cell, into the regular three-zooid stage as shown 

 in Figure 7, Plate I. 



This is the earliest and simplest known species of Pleurodic- 

 tyiim. In the succeeding formations of the Linden group, the 

 typical Helderbergian species, P. lenticulare, is quite common. 



Occurrence: Common in the Rockhouse shale at the sulphur 

 spring, 5 miles southeast of Savannah, and at Rockhouse, both 

 on Horse Creek, Hardin County. 



CLASS BLASTOIDEA 

 FAMILY CODASTERID^ 



Codaster lorae, n. sp. 



Plate II, figs. I, 2 



Description: This rare httle blastoid resembles C. attennatns 



and C. canadensis of the Middle Devonian. The calyx is an 



inverted pentagonal pyramid with an obtusely pyramidal summit. 



