158 SYNOPSIS OF BRITISH SEAWEEDS. 



C. Daviesii rary generally infested by parasites still more 

 minute than itself, particularly in and about the axillary 

 ramuli. I do not find it so generally fertile as C. - 

 tulum; the crowding of parasites, and collection of dirt 

 about the ramuli, where the tetraspores are borne, proba- 

 bly destroying the fructification. 



279. virgatiilum {The little twig Callithamnion) ; rose-red, mi- 

 nute, tutted, much branched; branches long and straight, 

 erecto-patent, alternate or secund ; ramuli from every joint 

 short, obtuse, mostly secund ; articulations thrice as long as 

 broad; tetraspores scattered along the branches, //"re. hi 

 Hook. Br. Ft. v. 2. p. 3 A9. (Atlas, PI. LX. Fig. 282.) 

 Callithamnion Daviesii, var., Harv. 



Hab. Parasitical on Ceramium rubrum, in pools between tide- 

 marks. 

 C. virgatulum and C. Daviesii appear to be very dis- 

 tinct one from the other, and easily recognized at a glance : 

 — the former distinguished by the uniform production of 

 snort ramuli along all its branches, which thus have the 

 appearance, under the microscope, of budding rods ; the 

 latter known by having a few longish ramuli crowded to- 

 wards the axils of the branches, while the rest of the branch 

 is bare. But in practice I find it by no means easy to dis- 

 tinguish these supposed species. There is no lack of spe- 

 cimens, which are thus clearly distinguishable ; but then, 

 on the other hand, there is no lack of intermediate forms. 



