V. RHODOSPERME.E. 5 



species, many of tliem grouping together plants but little related, and others sepa- 

 rating nearly allied species. Still, we are indebted to Kiitzing for reforniing many 

 of the old genera left untouched by earlier writers. I regret that in his more recent 

 ^'■Species"* he has pursued the deforming, rather than the reforming course, intro- 

 ducing innumerable false species, further subdividing genera, and even placing the 

 same species in two or more widely separated genera. 



I turn with pleasure to the work of a very different writer, Prof J. G. Agardh, 

 whose ''^ Species, f Genera, et Ord'mes A/garum, now in course of publication, places 

 him, for accurate analysis, careful description, original conception, and just views 

 of system, far above any other author Avho has devoted his attention to the Algfc. 

 In his former works he had sketched out the system which he has now more fully 

 developed, has fortified by the examination of a very large number of species, and 

 remodelled where alterations were necessary. The primary distribution into Orders 

 is based on the structure and development of the sporiferous nucleus, which affords 

 excellent discriminative characters. In the generic groups minute attention is paid 

 to the anatomy of tlie frond, the position and partition of the tetraspores, the minor 

 structure of the conceptacle, &c. The result, I trust, will be to place the systematic 

 arrangement of the Algae on a better and firmer foundation than it has yet stood. 

 I have carefully gone over, with the dissecting knife and the microscope, much of 

 Prof Agardh's ground, and tliough I do not follow him in all the changes he has 

 introduced, the points where we differ are few and unimportant, and open to future 

 consideration. "With the principles advocated in his system I fully coincide ; I dif- 

 fer merely in a few cases where it seems to me, perhaps incorrectly, that natural 

 affinity has been mistaken. 



I take this opportunity to record the expression of my best thanks to those kind 

 correspondents and friends in America who continue to supply me with specimens. 

 Since the publication of the first part, I have received from Captain Nicholas Pike 

 of Brooklyn an important contribution of Californian Algas ; from Dr. Blodgett 

 of Key West a second interesting series of Floridan Alga>, containing some new 

 forms; from Mr. Hooper a parcel from the North-eastern States, containing several 

 not previously sent ; and from Mr. Calverley, Algae of New York Harbour, &c. 

 These and other contributions will be found duly noted under each particular spe- 

 cies in the body of the work ; and should any novelties reach me before the publi- 

 cation of the third fasciculus, they shall be inserted in a supplement. Persons in 

 America wishing to assist me with further specimens are rer|uested to send parcels 

 addressed to Dr. William H. Harvey, Trinity College, Dublin, to the care of Messrs. 

 Abraham Bell and Son, 25, Park Row, New York ; or to J. Van Voorst, Publisher, 



1, Paternoster Row, London. 



W. H. H. 



Tkix. Coll. Duni.rK, 

 November •2ilh, 1852. 



* Species Algarum, auctore F. T. Kiitzing, Lipsise, 1849. 

 t "Species, Genera et Ordines Algarum, auctore J. G. Agardh." Lund, 1848-1852. 



