LKIAi ri. 156 



extreme forms T have seen too many intermediate e 

 to admit of my regarding them as belonging to more than 

 one specific type. The nearest affinity of the plant is with 

 igiosum, a species much more densely branched and 

 busty, of a browner colour, with a wry robust stem and 

 short articulations; but, like the present, remarkable 

 for dichotomous, Level-topped ramuli, and tet raspores placed 

 opposite the alternate forki 



272. spongiosum ( TL<- spongy CcUlithamni obust, 

 cartilaginous, more or less opaque and veiny, branched in 

 every direction ; branches thickly set with dense, quadrifa- 

 rious, repeatedly dichotomous, round-topped branchlets; 

 axils patent : apices short, bifid ; articulations of the branches 



len at the joints, twice or thrice as long a> broad, Harv. 



in Hook. Br. Ft v.2.p. 346. (Atlas, PL L\ II. Fig.265.) 

 Ilah. On perpendicular submarine rocks, near low-water mark, 



and parasitically on other Algse. Annual. Summer. 

 Callithamni-on spongiosum has much the external ap- 

 pearance of C. arbuscula ; but its microscopic characters 

 are so different, that they belong to separate sections of 

 the genus. It is much more nearly allied to ('. corym- 

 bosum or the exotic C. granulatum, a south of Europe 

 Species, which lias so much in common with it that I shall 

 surprised if future observations lead to their being 

 united. From C. corymbosum, the duller colour, shorter 

 joints, more robust and opaque stems, and dense, spongy 

 nabit, sufficiently distinguish it. It is curious that it ap- 

 pears to OCCUpy the place of C. arbuscula on shores where 

 the latter is not found, these plants never growing toge- 

 ther, though both affect similar situations on different 

 shon 



273. pedicellatum (The pedicellate CallUhamnio 



taceoue, pellucid, jointed, loosely and inegularh divided; 

 branches furnished with short, alternate, sparingly dichoto- 

 mous, ramuli; apices very obtuse; articulations variable, 

 mostly very long ; tetrasporee (?) solitary, elliptical or | 

 shaped, axillary, Btalked, Ag. Sp,Alg,v.2.p. 17 1. {A 

 PL l.X. i 

 Callithamnion clavatum, Ag. C. Ferreymondii, I * . botry- 



ticum, I)' Not. Ghriffithsia irregularis, Ktz. Ceramium pe- 

 dicellatum, Ag. 0. claysBgerum, Bonn, Conferva pedicel* 

 lata. E. Bot. 



