No. 5] NEW OR CRITICAL CALCAREOUS ALGÆ. 23 



A specimen in Bornet's herbarium from Key West, Florida 

 (leg. Farlow) stands very near to the present spedes, the crust 

 being, however, more continuous and the structure more regular. 

 I have not seen heterocysts between the epidermal cells, but here 

 and there in the perithallic layer appear the above mentioned large 

 cells. It also shows here and there on the surface a layer of 

 subhyaline cells agreeing with similar formations in the true O. 

 Notarisii. However, I am uncertain whether it is to be considered 

 a separate species or not, as I have seen but a solitary specimen 

 and the present species being much varying. 7 his specimen also 

 shows a near connection with the following species. 



Goniolithon (Cladolithon) elatocarpum Fosl. mscr. 



Thallus crustlike of indefinite extent, up to about 7 mm. thick, 

 with frequentl}'' small wartlike excrescences. Conceptacles of 

 sporangia 500 — 700 y. in diameter, with an elongated tip soon 

 falling away and then hemispheric-conical. Sporangia bisporic 

 about 100 <J- long and 50 /a broad. 



In British Museum is to be found a solitary specimen of the 

 present alga which, on the one side, is closely related to Oonio- 

 lithon Notarisii, but on the other so much dilTering that I venture 

 to regard it a separate species. 



The said specimen is fragmentary, nearly 6 by 4.5 cm. in 

 diameter and appears to have form ed a part of a larger crust of 

 indefinite extent. ln the thickest part the crust is about 7 mm. 

 thick, plainly decreasing in thickness towards the rather thin mar- 

 ginal portion. The surface is uneven, provided with small wart- 

 like or more or less irreguiar and low excrescences, some of which 

 are due to growing over of the conceptacles of sporangia or extra- 

 neous objects. The colour is a dark rosy with a purplish shade. 



The conceptacles of sporangia are scattered, 500 — 700 /j. in 

 diameter, with elongated tip, including the latter up to about 1.5 

 mm. high, but the tip soon falls away and then the conceptacles 

 are hemispheric-conical, with thick w^alls, and at length growing 

 down into the frond. The sporangia are two-parted, however only 



