Butters: OBSERVATIONS ON TRICHOGLCEA LUBRICA. 15 



forming the smaller filaments of the medulla. Their general 

 course after reaching the medullary region is approximately 

 longitudinal and usually towards the base of the frond, but they 

 sometimes turn upward toward the growing point, and a cross- 

 section of the frond often shows them running in various oblique 

 directions among the primary filaments (Fig. 7). 



The production of the secondary cortical filaments and of 

 these smaller medullary filaments continues for a long time, so 

 that the branch systems become finally very intricate (Fig. 4)- 

 Even in the older parts of the frond immature cortical filaments 

 may frequently be found among those which have long been 

 mature (Fig. 14). In the mature frond there are somewhat 

 large spaces among the cortical cells close to the medulla, and 

 it is % in these spaces that the calcium carbonate is deposited 

 which incrusts the medullary region of the frond (Fig. 6). 



In mature parts of the frond the diameter of the principal fila- 

 ments of the inner cortical region is greatest close to their origin 

 from the medullary filaments. The cells here average 65 x 12 

 mic. Farther from the medulla the cells are often longer, but 

 more slender. Still farther out the cells are again shorter and 

 wider, and pass by a gradual transition into the almost spher- 

 ical cells of the assimilating area. 



The outer cortical assimilating area of the frond consists of 

 moniliform filaments, simple or somewhat sparingly branched 

 in their proximal portions. In the region of transition from the 

 inner cortex, the cells are somewhat elliptical, with an average 

 size of 24 x 12 mic. In the distal parts of the filaments the cells 

 are slightly wider and much shorter, so that they are almost 

 spherical or often a little flattened, averaging about 14 x 15 mic. 

 The terminal cell of a mature filament is usually somewhat 

 smaller than th'e cells immediately proximal to it. In the ma- 

 turation of a filament one or more of the distal cells frequently 

 fail to round up, and finally break down, leaving the filament 

 capped by a loose floating mass of material resulting from their 

 deliquescence (Fig. 14). 



The general structure of the frond is thus seen to agree closely 

 with that which has been described in the nearly related genus 

 Liagora (Agardh, J. G., Analecta Algologica, III., 96. 1896) 

 and especially with that of the subgenus Euliagora (1. c., p. 

 97). Agardh describes the structure of Liagora viscida 

 (Forsk) J. Ag. as typical of this subgenus. He notes the two 



