122 SUPPLEMENT. 



then becoming clubshaped and somewhat inflated, from half an inch to an inch long, 

 crowned with a peltate horizontal lamina, Avhich is either subentire or sharply dentate 

 at the margin. In young specimens or on young branches the peltate leaves are found 

 flat and thin, their upper and lower surfaces forming one substance ; but more com- 

 monly the centre of the leaf becomes inflated or vesicated, and then is formed a compound 

 top-shaped flat-topped body, half vesicle, half leaf, which is characteristic of the genus. 

 Receptacles dichotomous, much branched, shrubby, their branches verrucose. Colour 

 when growing a pale olive, but in the herbarium changing to a dark brown or black. 

 Substance, when dry very hard and rigid. 



A common plant in tropical seas, both in the eastern and western hemispheres. Mr. 

 Ashmead obtained fine specimens at Key West, but it appears to be of rare occurrence. 



Part 1, page 64, add, 



III.* CYSTOPHYLLUM. 



(Generic character the same as that of Cystoseira, except that the air-vessels are 

 confined to the ultimate ramuli, which are simple and filiform.) 



1. Cystophyllum geminatum, Ag. ; stem ; fronds elongate, filiform, un- 

 armed, decompound-pinnate ; branches issuing from all sides, geminate ; vesicles solitary 

 in the ramuli near the summit, oval, tipped with an excurrent point ; receptacles 

 paniculate, warted, attenuate, often tipped with a vesicle. J. Ag. Sp. Alg. 1, p. 232. 

 Cystoseira thyrsigera, Post, and Rupr. 111. Alg. 13, t. 38,/. 4. 



Hab. Banks' Island, North Western America, Mr. Menzies, 1787. (v. s.) 



In Mr. Menzies' Herbarium, now preserved at the Botanic Garden, Edinburgh, is 

 a specimen of this plant, marked C. trinodis in Mr. Menzies' handwriting. Two 

 branches are laid on one piece of paper. The largest is about 10 inches long, as 

 thick as sparrow's quill, smooth, decompound, pinnate and ovato-lanceolate in circum- 

 scription. The branchlets are mostly geminate, filiform, alternately decompound ; 

 their lesser divisions also subgeminate. Vesicles oval, 1^ lines long, scarcely a line 

 wide, either solitary in the filiform ramuli, about the middle or a little beyond it, or two 

 in the ramulus, the second one terminal, apiculate, and removed by a rather long pedi- 

 cel from the first. Receptacles lanceolate, 2-3 lines long, verrucose, apiculate, often 

 with a slender beak nearly as long as the receptacle, and sometimes two receptacles occur 

 on the same ramulus. The upper branches are very dense. 



Page 71, add, 



8. Fucus serratus, Linn. ; frond flat, dichotomous, midribbed, serrated, without air- 

 vessels; receptacles flat, terminating the branches, serrated. J. Ag. Sp. Alg. 1, p. 211. 

 Kiitz. Sp. Alg. p. 590. Turn. Hist. t. 90. E. Bot. t. 1221. Harv. Phyc. Brit, 

 t. 47, ^c. 



