DUBLIN UNIVERSITY BOTANICAL AND ZOOLOGICAL ASSOCIATION. 203 



nococcus Hennedyi. Fig. 2, fertile and barren filaments separated. 

 Fig. 3, a tetraspora 



4. Cruoria pellita (Fries.). — Crust of indefinite extent, dark-red 

 brown ; filaments much branched below, dichotomous, and somewhat 

 corymbose above, attenuated upwards ; tetraspores lateral, zonate, fusi- 

 form, J". Ag., Sp. Alg., vol. ii. p. 491 ; Aresch. in Linnsea, xvii. p. 267, 

 Tab. 9, Figs. 7, 8; Chcetoderma pellitum, Kiitz., Phyc. Gen., p. 326; 

 not C. pellita of Harv., Phyc, t. 117.— Tab. XIII. B. 



On rocks, &c, between tide-marks, on several parts of the coast ; 

 Miltown Malbay, 1831 (W. H. H.) ; Sound of Jura (Professor Walker 

 Arnott) ; Cumbrae (Mr. Roger Hennedy). 



This forms a scab -like, tough, dark-brown, or reddish crust, on the 

 surface of rocks, to which it adheres very closely. The crust is wholly 

 composed of vertical filaments, which are much branched, and robust 

 at the base, and gradually taper upwards, becoming less frequently di- 

 vided, and more regularly dichotomous. Large zonate spores of dark- 

 red colour, ellipsoid or fusiform, often much pointed, are found hidden 

 among the filaments, and are formed by the transformation of one of the 

 branches. I am indebted to Professor Walker Arnott and Mr. Hennedy 

 for specimens in fruit. 



In the " Phycologia Britannica" I have figured a very different 

 plant, namely, Petrocelis cruenta {J. Ag.), under the name Cruoria pel- 

 lita ; a mistake into which I ought not to have fallen, as I appear to 

 have had both plants for many years in the Herbarium. Both form 

 crusts on rocks, and to the naked eye are undistinguishable. Under the 

 microscope, however, the Petrocelis is seen to be formed of simple fila- 

 ments, having when in fruit a single cruciate tetraspore formed in the 

 middle of each filament ; while the Cruoria, now described, consists of 

 much branched filaments, bearing zonate tetraspores. The figure given 

 in Phyc. Brit., 1. 117, represents the half-ripe state of the Petrocelis; in 

 ripe specimens the large central cell becomes a tetraspore. 



Plate XIII. B, Fig. 1, part of the crust of Cruoria pellita, magnified. 

 Fig. 2, portion of a filament. Fig. 3, a tetraspore. 



5. Cruoria adherens (J. Ag.). — Crust of indefinite extent, brown-red 

 or olivaceous ; filaments parallel, sparingly dichotomous, attenuated 

 upwards ; tetraspores lateral, zonate (J. Ag., Sp. Alg., vol. ii. p. 491). 



On rocks between tide-marks, in various places : Kilruggan, oppo- 

 site Gouroch (Professor Walker Arnott) ; Aberdeen (Dr. Drickie) ; Pen- 

 zance (Mr. Ralfs) ; Kilkee, 1844 ; Cushendall, Co. Antrim, 1850 

 (W. H. H.). 



Yery similar to the preceding, but with less branched threads. 

 Professor Arnott communicates specimens with tetraspores. I have also 

 received from the same liberal correspondent mounted specimens of a Cru- 

 oria (?) which is figured in our Plate XIII. C, but which I am uncertain 

 whether to describe as a new species, or, perhaps, the type of a separate 

 genus, under the name C. Arnottii, or to regard as the cystocarpal state 

 of C. adhcerens. The filaments are subsimple, or sparingly dichotomous, 

 as in C. adherens, but are of a smaller diameter, with snorter articula- 



