16 ' REVIEWS. 



between the Algae 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- 

 lares Digenia simplex, Acanthophora, Amarisia multifida, and other 

 West Indian Rhodosperms, are abundantly cast ashore. Sargassum 

 Vulgare and bacciferum Padnia Pavonia, Zonaria lobata and sundry 

 Dictyota, are characteristic Melanosperms. But this region is especially 

 remarkable for the abundance and beauty of its Chlorosperms, of the groups 

 Siphonaceae and Caulerpacea3 ; 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, Dictyosphwria, Chamadris, Dasycladus, 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 Delesseria?, 

 (D. involvens and D. tenuifolia) are specially worth notice. These 

 were very plentiful in the beginning of February, but soon disappeared. 



