176 MINNESOTA BOTANICAL STUDIES. 



According to the descriptions the first two species of Constan- 

 tinea differ in the length of stipe between annuli, the mode of 

 branching of the stipe and in the nature of the edge of the frond. 

 The following are also noted : Constantinea rosa-marina is the 



O 



smaller (one-half foot or less) ; branched even to the base ; termi- 

 nal frond two inches in diameter, laciniate (lacinise 3-6), rarely 

 remaining entire ; 24 laminae under the terminal one laciniate 

 in a similar manner. C. sitchensis has solitary terminal fronds 

 at the apices of the branches ; the fronds are 4-6 inches in 

 diameter, entire but laciniate when older ; young fronds are 

 often 8 lines in diameter. 



In these supplementary descriptions all differences are com- 

 promised except the following: length of the " internode " of 

 the stipe ; the number of fronds on each branch ; the method of 

 branching of the stipe and the difference in size. The tetra- 

 spores of C. sitchensis alone are described. The " gongyli 

 rotundi " as Kiitzing* has since pointed out are but ordinary 

 cells of the intermediate layers of the frond. Postels and Ru- 

 precht also mention Constantinea reniformis, a rare Mediterran- 

 ean plant supposedly of this genus. 



In 1843 Zanardinif described the C. reniformis of Postels 

 and Ruprecht under the name of Neurocaulon foliosuni from 

 material collected on the shores of Dalmatia in the Adriatic. In 

 the same year KiitzingJ called attention to the incorrect view of 

 Postels and Ruprecht concerning the " gongyli rotundi " and to 

 the great similarity in vegetative structure but great difference 

 in outward appearance and tetraspore formation between Con- 

 stantinea and Euhymenia. He describes the tetraspores and 

 states that the cystocarps are unknown. His statements are 

 evidently based solely on Postels, and Ruprecht's observations. 



In Species Algarum, 1849, the two arctic species of Postels 

 and Ruprecht are described under Neurocaulon as N. rosa- 

 marina and N. sitchensis. 



Two years later J. Agardh || accepts the Postels and Ruprecht 

 generic name of Constantinea and adds to the previous descrip- 

 tion of the vegetative parts and tetraspores that of the cysto- 



* Kiitzing. Phyc. Gen. 400. 1843. 

 tZanardini. Saggio class. 49. 1843. 

 t Kiitzing. 1. c. 



Kiitzing. Spec. Algar, 744. 1849. 



|| Agardh, J. Spec. Gen. et Ord. Algar. 2 : 295. 1851. 



