266 Mr Mackay's Flora Hibernica. 
known species introduced for the first time into our Flora, besides a 
new genus called Syncesia, constructed to receive a rather obscure 
plant allied to Arthonia* Dr Taylor has performed his share in the 
Flora Hibernica admirably ; and we are only disposed to complain 
of his having adhered too rigidly to the genera of Acharius after they 
have been, by universal consent, more or less modified. 
The last division of the work, devoted exclusively to the Algce, 
has been contributed by Mr Harvey, whose intimate acquaintance 
with the order is sufficiently shown in Hooker's British Flora. It 
is a department as full of interest, as the objects themselves are of- 
ten graceful and beautiful. Mr Harvey has done his part well and 
carefully. The Algce Britannicce of Dr Greville has to a considerable 
extent served him as a guide, and he has adopted verbatim, with due 
acknowledgement, that author's description of the Diatomacece, as 
contributed to the British Flora. But Mr Harvey is no copier, 
he plainly investigates and thinks for himself; and his portion of the 
Flora Hibernica contains much valuable information. All the Irish 
Algae he has arranged into three grand divisions, which, from the 
colour of the seeds, he denominates MELANOSPERMEJE, RHODOSPER- 
ME^E, and CHLOROSPERME^E. In the first division we find the tribe 
Ectocarpece placed between Dictyotece and Chordariece ; and in the 
second division, Gloiocladece, the first tribe, containing the genera 
Mesogloia, Gloiosiphonia and Chcetospora, precedes the Gaslrocar- 
pece. Such an arrangement exhibits new and ingenious views re- 
specting the affinities of Eclospermece and Gloiocladece. 
In order to add some degree of interest to this article, we have 
drawn up a table, which exhibits at one view the relative Floras of 
England, Scotland, and Ireland, in regard to the total number of ge- 
nera and species in each natural order ; as well as a list of those 
British genera in which the Irish Flora is deficient. 
* Ord. LICHENES. Genus SYNCESIA. Thattus crustaceous. Apothecia ob- 
longo-elongate, stellato-radiata, aggregated and immersed in scattered thallodal 
verruca. Perithecium none. Lamina prolifera pellucid, supported on opaque 
vertical layers. 
