MONOGRAPH OF THE BRITISH SPECIES OF EUPHRASIA. 395 



membfanes of the young individuals were either not silicified, or 

 were imperfectly silicified, as proved by burning ; and they were 

 therefore capable of growth, and of attaining the full dimensions of 

 Coscinodiscus concinnus, without the intervention of auxospores. 



Both in spring and summer, I observed in several species of 

 ChiBtoceros a series of divisions of the cell-contents, obviously similar 

 to the divisions in Coscinodiscus, and doubtless preliminary to the 

 formation of reproductive bodies. In C. borealis this sub-division 

 of the contents is carried to four, eight, and sixteen; in C. cun-isetus 

 to four and eight; and in C. constrictus to four. Instances of higher 

 numbers in the latter two species may and probably do occur, but 

 they have escaped me. I have witnessed the actual processes of 

 division up to four ; but the farther sub-divisions into eight and 

 into sixteen are known to me only from finding instances of them 

 as accomplished facts. What the fate of these bodies may be I do 

 not yet know, but I hazard the view that they resemble the corre- 

 sponding bodies in Coscinodiscus in their life-history. 



Having obtained a supply of sea-water, I am endeavouring to 

 cultivate these organisms during the winter in two large tanks, and, 

 if possible, to secure a continuous series of observations. There are 

 enormous difficulties in cultivating such organisms in London, but 

 so far I have a prospect of success. 



There are numerous questions of both scientific and economic 

 importance to be settled in connection with the study of marine 

 vegetation. That little is known maybe inferred from the fact that 

 it was possible to make so many novel observations within so short 

 a time. I would venture to recommend to the Board that a survey 

 of the conditions be made farther out at sea, that we may know 

 how far these banks of diatoms, Peridiniea, &c., extend seawards, 

 especially in the early months of the year and in summer, or how 

 far they may be coastal in their occurrence. 



MONOGRAPH of the BRITISH SPECIES of EUPHRASIA. 



Prefaced by an Epitome of Pbof. Wettstein's Views on the Development 

 AND Distribution of the European Species. 



By Frederick Townsend, M.A., F.L.S. 



(Continueii from p. 336.) 



Part II. 



Description and Distribution of Species, &c. , 



List of Native Species and of Hybrids. 



PARVIFLORiE. 



1. [Euphrasia stricta Host.] 6. E. occidevtalis Weitsi. 



2. E. borealis Towns. 7. [E. latifolia Pursh.] 



3. E.brevipila Burn. eiGrem. 8. E. Eouhwnsis Towns. 



4. E.nemorosa H. Mart. 9. K. (jracilis Fries. 



5. E. curta Fries. 10. E. Scotica Wettst. 



