580 



Foslie and Howe : New coralline algae 



apparent at frequent intervals in a radio-longitudinal section 

 (figure 2, b and plate 26 ; see also Corallinaceae Siboga-Exped. 

 59), but the West Indian plant is rather coarser and is considerably 

 different in habit as will be seen by comparing our photograph 

 (plate 25) with that of L. craspedhim cited above, the branches 

 being more inclined to increase in size upward and anastomosing 

 in a more gyrose.or daedaleoid fashion. We believe it should 

 bear a distinctive specific name, at least until further collections 

 give better grounds for understanding the relationships of West 

 Indian forms to those of the South Pacific and Indian oceans. 



tphyllutn aft 



is less coarse than L. Antillarum* its 



branches are thinner, and more frequently subterete or compressed, 

 though sometimes dilated and rather foliar, its medullary cells 

 after decalcification are firmer-walled and more rounded at the 

 angles, and the short rows of enlarged cells are rare. 



Explanation of plates 23-26 



Plate 23 



Goniolithon acropetum, natural size ; the topmost specimen is the type. 



Plate 24 



Goniolithon acropetum. Photograph of a sagittal section (decalcified) of a flat- 

 tened branch, showing perithallium and portion of medullary hypothallium, magnified 



165 diameters. 



Plate 25 



Lithophyllum Antittarum, natural size, the upper specimen seen from above, the 

 lower from the side; the latter the type. 



Plate 26 



Lithophyllum Antillarum. Photograph of radio-vertical section (decalcified) from 

 the medullary hypothallium, magnified 165 diameters. The direction of growth is 

 towards the upper left-hand corner. 



