122 SYNOPSIS OF BRITlSn SEAWEEDS. 



LX1X. ITALY Al KM A. 



209. ligulata (The strap-shaped Halymenia) ; frond comp 



or Bat, irregularly dichotomous or palmate, the segments at- 

 tenuated, often proliferous at the margin, Ag. &p. AJg. r. 1. 

 510. (Atlas, PL \LVIli. Kg. 21(5.) 

 Halymenia elongata, Ag. Halarachnion ligulatum, A7:. XJhn 

 Hgnlata, Woodw. U. rubra, ffuds. BCesogloia Hudsoni, A g. 

 Hah, Frequent on the southern shores of England. On rocks 

 and >t<>in » mar low-water mark, rare ; more usually dredged 

 in 6-10 fathoms water. Amiual. Summer. 

 Among British Alga? few exhibit wilder variations in 

 form than this, and yet I have never known it to be mis- 

 taken by any person who has once had the advantage of 

 seeing it in a living state. The pinky colour, and pecu- 

 liarly soft substance, between gelatinous and membrana- 

 ceous, and the innumerable dots of fructification, are found 

 in every specimen, and sufficiently mark the species. In 

 form and size there is extraordinary variety. 



LXX. GINAXMA. 



210. furcellata (The forked Oinannia) ; frond cylindrical, ten- 

 der, uniformly dichotomous ; the segments obtuse, Mont. 

 PL Cell Can. p. 162. (Atlas, PL L. Fig. 226.) 



Halymenia furcellata, Ag. Myclomium rurcellatum, Ktz. Ulva 



furcellata, Turn. U. interrupt*, Poir. Dumontia triquetra, 



Lamour. Corallopsis dichotoma, Suhr. 

 Hah. Eastern and southern shores of England. On rocks, 



stones, oyster- shells, etc., from low-w r ater mark to eight or 



ten fathoms water. Annual. Summer. 

 Though this plant is so widely distributed, and ought to 

 be so well known, a very remarkable feature of its struc- 

 ture has been passed over by most authors who have de- 

 scribed it. I allude to the axis, or internal casta, which 

 exists in all specimens which have come under my notice, 

 though it is very much more apparent in some than in 

 others. Owing to the imperfect manner in which the 

 frond recovers its form on immersion, after having been 

 dried, this costa cannot always be shown by a transverse 

 cutting of a dried specimen ; but in the recent plant it 

 may at once be detected, even where most obscure. 



LXXI. KALLYMEXIA. 



211. reniformis (The kidney-shaped Kallymenia) ; stem short, 

 cylindrical, suddenly expanding into a roundish, subsimple 



