P l a t e CCLXXXVI.
LAURENCIA CÆSPITOSA, Lamour.
G en . Chau. Frond cylindrical or compressed, linear, pinnately branched,
the apices obtuse; structure cellular, solid. Fructijication of two
kinds, on distinct individuals; 1, ovate capsules [ceramidia), fm--
nished with a terminal pore, containing a tuft of pear-shaped spores;
2, triparted tetraspores, imbedded in the ramuli. L aurenoia
[Lamour.),—in honour of M. de la Laurencie, a French naturalist.
L aurencia cæspitosa; frond cylindrical or subcompressed, narrow, repeatedly
pinnate, pyramidal; main branches often opposite, erecto-
patent; ramuli irregularly scattered, distichous or spreading on all
sides, often crowded, erect, slightly tapering to the base, truncate.
L a u r e n c i a cæspitosa, Lamour. Ess. p . 43. Mont. FI. Crypt. Canar. p. 154.
Harv. Man. ed. 2. p. 98.
L a u r e n c i a l i y b r i d a , Lenorm. in Buh. Bot. Gall. p . 951. Harv. Phyc. Br.
v o l . i . p . x i i i .
L a u r e n c i a p i n n a t i f i d a , y a n g u s t a . Grev. Alcj. Brit. p . 109. Hooh. B r El.
v o l . i i . p . 296. Harv. M a n .'ÿ.6'b. Harv. Phyc. Brit, Wyatt,
Alg. Danm. no. 162.
Tucus h y b r i d u s , B.C. M. Fr. vol. i i . p . 30.
H ab. On stones and shells, within tide-marks; rarely growing on other
aiTia11 Algæ. Annual. Summer. Common on the shores of the
British Islands.
G e o g r . D i s t r , Atlantic shores of Europe. Canary Islands. Southern Ocean.
D e s c r . Root a c c o m p a n i e d b y c r e e p i n g f ib r e s . Eronds d e n s e ly t u f t e d , f r o m tw o
t o s i x i n c h e s i n l e n g t h , a b o u t h a l f a l i n e i n d i a m e t e r , o f n e a r l y e q u a l
b r e a d t h t h r o u g h o u t , c y l i n d r i c a l , o r v e r y s l i g h t l y c o m p r e s s e d , h a v i n g a p e r -
cm - r e n t u n d i v i d e d s t e m , s e t w i t h n u m e r o u s , a l t e r n a t e , o r r a r e l y o p p o s i t e ,
e r e c t o - p a t e n t b r a n c h e s , t h e l o w e rm o s t o f w h i c h a r e l o n g e s t , t h e u p p e r g r a d
u a l l y s h o r t e r , s o t h a t t h e w h o l e p l a n t h a s a p y r a m i d a l o r c o n i c a l o u t l i n e .
Branches r e p e a t e d l y p i n n a t e d , t h e i r d i v i s i o n s n a k e d a t b a s e , p i n n a t e d f o r
t h r e e - f o u i - th s o f t h e i r l e n g t h , a l l t h e d i v i s i o n s v e r y e r e c t , b l u n t , o r t r u n c a t e ,
e a c h u l t im a t e r a m u l u s f r e q u e n t l y b i - t r i f i d a t t h e p o i n t . Ceramidia . . . ?
Tetraspores c o n f in e d t o t h e a p i c e s o f t h e r a m u l i , n u m e r o u s , t r i p a r t i t e .
Colour, w h e n t h e p l a n t g r o w s u n d e r f a v o u r a b l e c i r c u m s t a n c e s , a v e r y d a r k ,
l u r i d p u r p l e : w h e n m o r e e x p o s e d t o t h e l i g h t , v a r i o u s l y g r e e n i s h o r y e l l
o w i s h . Substance c a r t i l a g i n o u s , b e c o m in g s o f t e r i n f r e s h w a t e r , a n d t h e n ,
u n d e r p r e s s u r e , s t r o n g l y a d h e r i n g t o p a p e r .
I offer this species with some hesitation, as it has hitherto
been generally considered by British authors a variety of L. pin-
N 2
i
hi