16 
REVIEWS. 
between the Algas of the Keys and those of the east coast, there is a 
marked affinity between the former and those of the south of Europe. The 
marine vegetation of the Gulf of Mexico has a very strong resemblance to 
that of the Mediterranean Sea; nearly one-third of the species collected 
are common to the Mediterranean. Several of them straggle onwards 
towards the coasts of Spain and France, and even reach the south of 
England; but scarcely any of those are seen on the east coast of America. 
From this we may infer that they are not conveyed by the Gulf stream. 
Those collected at Key-West included 10 Melanosperms, 5 of which are 
common to the Mediterranean ; 82 Rhodesperms, 25 of which are Mediter¬ 
ranean; and 38 Chlorosperms, of which 10 are Mediterranean. Besides 
these identical species, there are many representative , closely allied to the 
Mediterranean types. This resemblance is clearly shown in the genus 
Dasya , of which seven out of eleven European species are found in the 
Mediterranean. At Key-West eight species of this beautiful genus were 
collected. Among those, seven were new, and the eighth (D. Elgans) 
was found along the whole coast of North America. Three-fourths, per¬ 
haps, of the masses of sea-weed cast ashore at Key-West, belong to 
Laicreucia , of which genus several species, and innumerable puzzling 
varieties, are profusely common. A fine Hypnea , (described afterwards 
as Euchennia isiforme , J. A. S.), H. Wardemanni MS.), one of the 
most striking species of the genus is also abundant. Alsidium triangu- 
lare , Digenia simplex , Acanthophora , Amarisia multijida , and other 
West Indian Rhodosperms, are abundantly cast ashore. Sargassum 
Vulgare and hacciferum Padnia Pavonia , Zonaria lobata and sundry 
Dictyotce , are characteristic Melanosperms. But this region is especially 
remarkable for the abundance and beauty of its Chlorosperms, of the groups 
Siphonacese and Caulerpaceae; 10 species of Caulespa were collected, 
some of which are of common occurrence, and serve for food to 
the turtles, which, in their turn, are the staple diet of the islanders. 
Pencellus , at least three species, Udotea , Halimeda , Aceta- 
bularia , Anadyomene , Dictyosphceria , Chamcedris , JDasycladuSj Cymo- 
polia , and others, some of which are West Indian, some Medi¬ 
terranean, are evidence of the high temperature of the sea round the 
Keys. Many of the plants obtained at Key-West were cast up from 
deeper water when the south wind blew strongly, and were not seen at 
any other time. A visitor, therefore, in the hurricane months would 
procure many which escaped me. Among the species, two new Delesserice , 
(D . involvens and D. tenuifolia) are specially worth notice. These 
were very plentiful in the beginning of February, but soon disappeared. 
