864? Analysis of Scientific Books and Memoirs. 



panied Capt. Sir Edward Parry in his second voyage of discovery. The 

 Dictijotece, of which we have eight representatives in Scotland, and thirteen 

 in England, increase both in quantity and number of species as we ap- 

 proach the Equator. The Fucoideas, in a general sense, increase as we leave 

 the polar zone, especially in the variety of species. But the natural groups 

 into which they are separated, are strongly marked in their distribution. 

 The Fuci flourish between the latitudes 55° and 44", and, according to 

 Lamouroux, are rarely seen nearer to the equator than 36°. Fucus ser^ 

 ratus is entirely confined to Europe. If the imperfectly known Macro- 

 icystis comosa and Menziesii should prove to be true Fuci, the latter will- 

 be an exception to the rule, as it is said to be found at Trinidad, as well 

 as on the western coast of North America. The large genus Cystoscira is 

 found between the 50th and 25th degrees of latitude, becoming more plen- 

 tiful as the Fuci diminish. In New Holland, remarkable alike for its ve- 

 getable and animal productions, a distinct group of Cystoseirce predomi- 

 nates, as singluar in the water as the aphyllous Acacia are on the land. 

 Their stems are compressed, often appearing to be jointed ; the branches 

 spring from the flat side, and not from the angles, and are deflexed at 

 their insertion ; besides which, their vesicles are solitary and pedicellate. 

 This most extraordinary and local group, including some new species kindly 

 communicated to me by Mr Eraser, the colonial botanist at Sydney, is al- 

 ready known to consist of twenty species. The genus Sargassum, the 

 most extensive of the Fucoideco, comprising- above seventy species, is nearly 

 confined to the two tropics, and examples rarely occur beyond the 42d de- 

 gree in either hemisphere. The Red Sea is full of Sargassa. It is prin- 

 cipally to one or two species of Sargassum that the popular name of gulf- 

 weed has been applied by mariners. The prodigious accumulation of these 

 plants were first encountered by the early Portugese navigators ; Columbus 

 and Lerius compare them to extensive inundated meadows, and state that 

 they absolutely retarded the progress of the vessels, and threw the sailors 

 into consternation. Such accumulations occur on each side of the Equator, 

 in the Atlantic, Pacific, and Indian oceans." — " In the genus Sargassum 

 is observed a small group, as local and almost as peculiar as that we have 

 shown to exist in Cystoscira. This occurs in the seas of China and Japan, 

 and consists of Sargassum fulvellum, microceratium, macrocarpum, sisym- 

 brioides, Horneri, pallidum, and hemiphyllum, distinguished from the rest 

 by terminal fructification, a slender habit, small nerveless leaves, and often 

 elongated vesicles. 



** The Laminariece, among which are the giants of the marine flora, ex- 

 hibit., in a broad view, a tolerably decided geographical distribution. The 

 Laminarice predominate from the 40th to the 65th degree of latitude; while 

 the Macrocystes seem, as far as we know, to exist from the equator to about 

 45° of south latitude. 



" The only order of any extent remaining to be noticed is Flori- 

 decs. This order, generally speaking, belongs, according.to Lamouroux, to 

 the temperate zones ; and in this conclusion I think he is correct. But, 

 as might be anticipated, in an order which contains so large a number of 

 genera and species, there are many exceptions. The genus Amansia is 



