(92) 



the stability of this species, at least as at present characterised. We 

 have seen no specimens with favellcc (?) so characteristic as those from 

 Torquay, but specimens otherwise agi'eeing very well with the descrip- 

 tion in Phyc. Brit, are not uncommon, and if we are correct in our ideas 

 of the species, it does not seem to be of rare occurrence : at the same time 

 we are by no means certain of the permanency of any of the characters. 

 Specimens of C. ruhrum are very common, with wart -like excrescences, 

 much like the favellse of G. Botri/ocarpum, scattered over the whole plant, 

 while specimens are equally conmion with some of the apices straight, 

 and others forked and incurved. C. ruhrum, however, is such a variable 

 plant, even in the number of its involucral ramuli, that we have often had 

 our doubts whether more than one species was not still included under 

 the name. Professor Harvey remarks that the present species may 

 be known from C. rithnim by its peculiar favellee and the straight 

 apices of the branchlets, but expresses his doubts as to the favellee. 

 We must acknowledge a similar doubt, not having been able to find 

 anything like true spores in any of them ; they appear, in fact, to be 

 nothing more than warty excrescences filled with endochrome, somewhat 

 more condensed and granular than that in the ordinaiy cellules of the 

 plant, and very much resembling those commonly found on C. ruhrum as 

 well as on Hypnea purpurascens, Fucus vesiculosus, and many other Algse. 

 Many of the specimens sent under the present name, we have been 

 reluctantly compelled to refer to C. ruhrum, particularly a slender fonn 

 with a single involucral spine under the cluster of favellse. This spine 

 is generally rather more slender and rather larger than usual, and is 

 sometimes so much elongated as to give the fruit the appearance of 

 being axillary. 



CERAMIUM BOTRTOCARPUM. 



EXPLANATION OF DISSECTIONS. 



Fig. 1. — Kamulus with favellae ? 

 2. — Same. 



3. — Portion of ramulus witli tetraspores. 

 4. — Tetraspore from same. All magnified. 



