72 " Cincinnati Society of Natural History. 



species, as there is not sufficient difference between the two to 

 justify a separation. The only essential difference is the 

 occurrence in H. knotti of oscula, which are scattered over 

 the surface, these being absent from //. siibramosa. The im- 

 ])crfect preservation, however, might readily account for the 

 absence of these in the latter species. The canals, too, are 

 smaller in H. knotti than in the other. Both occur in the 

 same locality in Kentucky. 



2. — H. ASPERA, Ulrich, 1S89. 



Irregular in growth, " forming thick, shapeless fronds or 

 strongly nodulated, lobate or sub-ramose masses, .several 

 inches in length." When well preserved, the surface rough, 

 the .spaces between the canals thin and with sharp promi- 

 nences at intervals ; canal apertures irregular, often sub- 

 (juadrate, 0.5 mm. in diameter, with 7 or 8 in 5 mm.; in the 

 nodular examples, canal mouths .sometimes dispo.sed in a 

 radial manner, but without oscula at the center of the area ; 

 canal apertures sometimes wanting. (Ibid, pp. 241, 442.) 



Locality. — Marion and Lincoln Counties, Kentuckv. 



