MARINE AI/LE. 



II.-CORALLINACE^E. 



By M. FOSLIK. 

 LITHOTHAMNION COULMANICUM. 



AMONG the Natural History collections made in the Antarctic regions by the 

 'DinoYery* Expedition are some specimens of a calcareous alga, which has l>oon 

 kindly sent me for determination. They proved to represent a species new to science 

 belonging to the genus Lithothamnion, which I shall now dcscril)c. The species has 

 Iwen shortly mentioned in " Det Kgl. nornke Videnskaliers Selskalw Aarsberctning " 

 for 1904, p. 16 (Trondhjem, 1905), under the name of 



LITHOTHAMNION COULMANICUM Iteuu. 



The plant forms incrustations on pebbles. The crust is closely adherent to the 

 sulistratum when young, but when older it is here and there rather easily detached, 



LmiOTHAMSIO* COCLMAXICCM FOM. NAT. 



particularly when attacked by animals or when covering extraneous object*. It is 

 thin, in the specimens brought home the tlii-kin-s- nt exceeding 800ft, fro<|iii'ntlv 

 being less, or about 300/i. The shape of young crusts is frojurntly more or less 

 irregular, but now and then almost circular, and so also when older, but then tin- plant 

 sometimes fully surrounds the substratum. It is sometimes in.li-iin< t >n-ntric 

 zonatc, and the edge is crcnulate or irregular. Several crusts are often found on the 

 same substratum. They may run into each other, in some cases not showing any 

 visible mark where the joining takes place, in others here and tln>r- forming slightly 

 elevated ridges. The nature of the surface is determined l>y that of the substratum. 

 If this is smooth the crust is also smooth, and shines slightly when young. Older 



VOL. III. .-' ' 



