INVERTEBRATES. 



GENUS TRACHYPORA. Edw. & Haime. 

 TKACHYPOKA AUSTIN:, (n. sp.) 



PI. XI, Figs. 1-la. Ib. Ic, Id. 



Corallum deiidroid, the branches generally cylindrical, some- 

 times irregular, from 15 to 25 rnm. in diameter, and infre- 

 quently divided. Corallites conical, diverging- from an imagi- 

 nary axial line to open on all parts of the free surface. The 

 calices all oval or circular, very variable in size, the larger 

 ones about 1.1 mm. in diameter, and either level with the 

 general surface, or with an elevated margin. Each orifice 

 is adorned with small tubercles or short ridges arranged in a 

 radiate manner around the calice margin. Openings of the 

 rorallites separated by dense calcareous tissue, of variable thick- 

 ness, but apparently always as wide ais, or wider than the 

 diameter of the tube orifices. 



Sections show that the tubes are prismatic and in contact 

 uith each other, that their walls are greatly thickened by a 

 calcareous deposit on the inner side of the tubes, and that the 

 amount of the thickening increases toward the orifices. Mural 

 pores of large size are present, but apparently not numerous. 

 Tab uke are best developed in the axial region, where they cross 

 the tube cavity at intervals equalling once or twice the diam- 

 eter of the tubes. Tangential sections show that the corallile 

 cavities are surrounded by blunt, thick septal ridges. The 

 walls are now composed of fibre-crystalline calcite, and the 

 change lias destroyed the finer details of structure. 



In all important respects the species here described resembles 

 the Trachypora ornata, Rorninger sp., from the Hamilton gr. 

 and I do not think any reasonable objection can be urged 

 against placing them in the same genus. Specifically they are 

 quite distinct, the corallum of Romiuger's species being much 

 smaller, the calices less variable in size and not so prominently 

 margined, nor are the interspaces so thick. 



Position and locality: Coal Measures. Labette Co., Kansas. 



Collector, A. C. Austin. 



No. 2596 of the Illinois State Museum, 



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