078 PALEONTOLOGY OF ILLINOIS. 



ADDENDA 



ISOTJIYPA (? TECTULIPORA) GOTHLANDICA 11. Sp. 

 PI. LIV, fig. 6, Gc. 



Zoarium irregularly infundibular, about 2 cm. in height and 

 the same in diameter at open upper end; base small. The zoar- 

 ium consists of a double network; its entire thickness is about 

 1 mm. Zocedal apertures on the outer side of the inner net- 

 work, invisible from the surface because of the great develop- 

 ment of the carinse and scalae prevailing in genera of this type, 

 and which form the false or non-celluliferous outer network. 



On the inner or "reverse" face of the zoarium the branches 

 average a little less than 0.3 mm. in width, are flexuous, and 

 seem to inosculate regularly, leaving oval fenestrules nearly as 

 wide as the branches; 15 fenestrules, measuring longitudinally, 

 in 1 cm.; 19 or 20 branches in 1 cm. transverely; surface of 

 branches striate. 



Obverse side with the carinse very strongly developed, their 

 summits expanded and connected transversely by scalse, two- 

 thirds as thick, at intervals equalling the development of the 

 true dissepiments, which always occur almost directly beneath 

 them. Outer surface of scalse and summits of carinse but little 

 convex, and marked with from three to five distinct parallel 

 lines, causing the two exposed faces of the zoarium to resemble 

 each other greatly. The only difference likely to be noticed is 

 that on the outer side the false fenestrules and branches are 

 respectively a little larger and thinner than on the inner face. 



Zooecia in two flexuous ranges on each branch, one on each 

 side of the carina, with 21 or 22 in 5 mm.; apertures subcircu- 

 lar, 0.1 mm. in diameter, with rather strong peristome. 



