173 



which closely resembles this species in habit, of the same size, but 

 partly less regular in outline, the crusts here and there confluent, 

 with the limits sometimes visible sometimes not, and the periphe- 

 rical portion slightly thicker, fully or almost fully passing into the 

 central portions. It bears scars after emptied conceptacles, some 

 of which are nearly effaced, or only the central portion of the roof 

 dissolved, showing that they are of the same size as in the pre- 

 sent species, but less distinctly marked. The colour is a faint 

 purplish pink. It hardly admits of doubt that this plant is identic 

 with the species in question, although the sporangia are unknown. 



Relation to otlier species. It is plainly distinct from any other 

 species that I know, perhaps most nearly allied with L. Strom- 

 feltii, but easily recognized and separated by essential characteristics. 



Habitat. The species probably grows on rocks in the litoral 

 region, supposing it has been referred to Melobesia polymorplia 

 recorded by Ekman 1. c. It appears to be furnished with spo- 

 rangia in summer. The above quoted British specimen has been 

 collected in August. 



Occurrence. Hitherto only met with at Christiansund, N. 

 •(Ekman). 



Geogr. Distribution. Britain (Batters). 



Lithothamnion Stromfeltii Fosl. mscr. 



Lithothamnion tenue Rosenv. Gronl. Havalg. p. 778. 



f. macrospora Fosl. mscr. 



f. plerumque nitida, concentrice zonata, margine lobato vel 

 crenato; conceptaculis sporangiferis diametro 600 -900^; sporangiis 

 250—600 p. longis, 100—200 fi latis. Tab. 22, fig. 12. 



f. tenuissima Fosl. mscr. 



f. subnitida, non vel parce zonata, margine sæpe irregulariter 

 crenato-lobato ; conceptaculis sporangiferis diametro 400 — 600 /*; 

 sporangiis 150 — 200 //. longis, 50—80 jj. latis. 

 Fig. Lithophyllum Lenormandi f. læve Fosl. Contrib. II, pl. 3, fig. 6. 



Syn. Melobesia Lenormandi Farl. Mar. Alg. New Engl. p. 181 ex parte? 

 Lithophyllum Lenormandi Gobi, Algenfl. Weiss. Meer. p. 21; ex parte. 

 „ „ Fosl. Contrib. I, p. 9; ex parle. 



