280 NOSTOCHlNEJi. 



Derivation. From a^avitppzvov, a vanishing thing. 



" It is evident that this genus unites the true Conjugates, 

 to the Zygnemata by a union well marked in the latter, but 

 being a simple soldering in the Aphanizomena : it relates the 

 Conjugates with the Laminarice of the sea by the form of the 

 lamella, which results from the soldering of the threads : it 

 establishes an analogy between the OscillatoricB and the Con- 

 ferva, by demonstrating that a movement of reptation, of 

 swimming, or of oscillation, may appertain also to the organi- 

 zation as of the Conferva as to that of the OscillatoricB) in 

 which the characters of animality are supposed to be recognised: 

 the inflated vesicles unite the Aphanizomena to the Conferva 

 vesicata of Agardh, and the cells as well as the organization 

 of the threads themselves maintain with the true Conferva 

 relations so clear, that it would be improper to place other- 

 wise than amongst them this new genus." - - Morren. 



The true position of the genus is undoubtedly amongst the 

 Nostochinea, uniting them with the Oscillatoria. The ana- 

 logies indicated by Bory are more imaginary than real. 



1. APHANIZOMENON INCUKVUM Morren. 

 Plate LXXVI. Fig. 6. 



Char. Lamella plain, whitish green, incurved. Threads 

 cohering. Cells from two to eight times as long as broad. 



Morren, in memoir read before the Royal Academy of 

 Brussels, in Dec. 1839: Thompson, in Annals of Nat. 

 Hist. vol. v. p. 82. ; Harv. in Manual, p. 145. 



Hob. In sheltered creeks, floating on the surface ; Bally- 

 drain Lake : W. Thompson, Esq. Grand Canal docks, 

 near Dublin : Professor G. J. Allman. In the pond of 

 the Dublin Zoological Gardens : Miss Ball. 



" Towards the middle of the month of May, up to July, the 

 waters of the lakes, the ponds, and the basins which surround 

 the country houses in Flanders are noticed to present tufts 

 of a whitish green, and of a size which varies from that of a 



