248 The Ottawa Naturalist. [March 



Carboniferous formation. One specimen the property of the 

 Redpath Museum, McGill University, Montreal. 



LONSDALEIA PiCTOENSE, Billings, sp. 



Lithostrotion Picioense, Billings. 1868. Dawson's Acadian 

 Geology, second edition, p. 285, fig. 83. 



Corallum compound, fasciculate, composed of long, upright, 

 flexuous, cylindrical corallites that increase freely by lateral cali- 

 cinal gemmation and are separated from each other by spaces of 

 variable width though frequently in contact. Corallites attaining 

 a breadth of about 10 mm , the young ones beginning with a 

 diameter of between 2 and 3 mm. Ejiitheca complete. Internal 

 structure consisting of a circumferential vesicular zone, in breadth 

 equal to about one-fifth the diameter of the corallite, defined 

 within by a stout inner wall that encloses a tabulate area at the 

 centre of which is a comparatively large columella about i mm* 

 in thickness. From the inner wall converge short, strong, well 

 defined septa that are occasionally extended outward into the 

 vesicular zone and more rarely reach the outer wall. The septa 

 extend only about half-way across the space between the inner 

 wall and the columella ; alternating with them are observed 

 occasionally rudimentary septa which are also indicated in the 

 outer wall in those exceptional instances when the primary septa 

 traverse the peripheral vesicular area. Tabulae moderately 

 regular, about twelve in a space of 5 mm., inclined slightly up- 

 ward at their junction with the inner wall and rising suddenly 

 and inosculating with each other near the centre so as to form 

 the columella. Vesicles of the outer area long and narrow, 

 formed by curved plates rather unequal in size, that are directed 

 obliquely upward and outward and fill the space between the 

 two walls. 



Represented in the collection by a small fragment, roughly 

 4 cent, broad and over 2 cent, high, embedded in compact lime- 

 stone that hides the exact characters of the surface of the 



corallites. 



