300 



MARINE ALG^ OF THE SCARBOROUGH DISTRICT. 



By GEORGE MASSES, F.R.M.S., 

 Scarborough ; Secretary for Cryptogaviia to the Botanical Section of the 

 Yorkshire Naturalists Ufiiou. 



The Scarborough district includes the coast between Scalby Mills 

 on the north, and Carnelian Bay on the south, a distance of about 

 five miles. A few additional species are stated to occur within these 

 limits, but as they have not been collected, and specimens are not 

 forthcoming, they are not inserted. To Mr. J. T. Milow, of Fals- 

 grave, I am indebted for several of the rarer species. 



CR YPTOPHYCEM. 



Glaeocapsa crepidinum Thuret. 



Rocks at high water. 

 Clathrocystis roseo-persicina Cohn. 



On decaying algje. 

 Dermocarpa prasina Bornet. 



Common on the smaller Floride^. 

 Xenococcus schousboei Thur., Notes Algologiques, pp. 73-75, pi. 26, 

 figs. I, 2. 



On Ceramium rubrum. New to Britain. 

 Spirulina tenuissima Kutz. 



Mixed with other small forms on the Spa wall. 

 Oscillaria subuliformis Thwaites. 



Scalby Beck, in brackish pools. 

 Microcoleus chthonoplastes Thuret ( = M. anguiformis Harv.) 



Mixed with Confervas. 

 Hormotrichum cutlerise Harv. 



Rare. Near the North Pier, where freshwater drains down the cliff. 

 Forming a thin bright green layer; plants unbranched, flexuous ; 

 cells at first quadrate, the contents soon becoming resolved into 

 a globose mass, which afterwards becomes pyriform, the longest 

 diameter being transverse to the axis of the plant, and eventually 

 escapes as a zoogonidium, furnished with two cilia at the narrow 

 colourless end. 

 Calothrix confervicola Ag. 



Not uncommon on species of Ceramium. 

 Calothrix scopulorum Ag. 

 Rivularia atra Roth. 



On rocks. South Bay. 

 Isactis plana Thur. 



On Hima?ithalia lorea. Rare. The only other British station 

 is Ventnor. 



Naturalist, 



