132 FOSLIE, MELOBESIA CASPICA, A NEW ALGA. 



bourhood of tlie conceptacles where two or three layers are to 

 be found. Confiuent crusts gripe over each other. On the other 

 hand, attached to small sliells are frequently to be found two 

 or three crusts one above the other, and sometiraes even stret- 

 ched over conceptacles of the primary ernst, and thereby in 

 some cases apparently becoming squaraulose-imbricate, as the 

 new crusts often do not anastomose but resemble scaly thicken- 

 ings scarcely visible to the naked eye. The thickness of the 

 crust is 25 — 40 jW, but in parts where more crusts than one are 

 formed over each other the thickness gets up to 130 f.i. 



A section of the crust shows the basal cells to be elongated 

 vertically, 22 — 35 f.i long and 10 — 14 f,i broad, partially covered 

 with small cortical cells which are squarish or roundish. Some- 

 times the cortical cells of a subjacent crust are found to be 

 very feebly developed before a new crust Stretches itself over 

 the former. The walls of the cell-rooms are raost frequently 

 rather thickened, with more or less rounded corners. 



The conceptacles of sporangia are sometimes rather scattered, 

 sometimes and most commonly densely crowded and occasionally 

 even to that degree, that the roofs become angular. They are 

 hemispheric-conical, 200 — 250 f.i in diameter at the base, with 

 a Single central orifice. The sporangia are four-parted, 55 — 65 

 f.1 long by 20 — 30 f.i broad. 



Regarding the colour it appears to he rosy. The specimens 

 are however bleached having been kept partly in alcohol, partly 

 n other liquids. 



On the one hand the species shows some relation to Der- 

 matolitlion pusüdatum (Lamour.) as regards the structure or 

 especially the basal cells, but differs both in habit and chiefly 

 the conceptacles of sporangia. On the other hand, it appears to 

 approach to Melohesia myriocao'pa Gr., a species as yet not 

 well known and only found on the west coast of France, but 

 most probably being specifically distinct. 



The present alga seems to be widely dispersed in the Cas- 

 pian. The specimens communicated by Prof. Andrussow are 



