FIFTH REPORT OF THE DIRECTOR 1908 



203 



Professor Hall referred originally to his O 1 d h a m i a 

 c o s a intertwining slender branch- 

 es which have been separated by 

 Professor Whitfield and described 

 as Chaetomorpha ? pri- 

 ma [see text fig. 9, 10]. A speci- 

 men on the same slab with some of 

 the types of Callithamnop- 

 sis fruticosa reproduced in 

 plate I, figure 4, leaves, however, 

 no doubt that these stems twisted 

 together are but branches of the 

 latter species which in drifting 

 have become stripped of the 

 branchlets of the higher orders and 

 at the same time through their flac- 

 cidity became twisted around each 

 other. 



The specimen here figured dem- 

 onstrates at the same time that the 

 main branch of C. fruticosa 

 bifurcated once or twice, the result- 

 ing branches bearing pairs of chaetomorpha ? prima 

 branchlets. , ' Fl %?^g -T ype s ^ ecimens - 



from Whitfield) 



Callithamnopsis delicatula sp. nov. 



Plate 1, figure c; plate 2, figures 1, 2 



Description. Thallus consisting of segmented monopodial or 

 bifurcating main branch bearing whorls of branchlets which in 

 their turn divide repeatedly in whorls of branchlets of higher order. 

 The main branch is apparently bifurcated. At least such a division 

 is indicated by the specimen plate 2, figure I, and it would agree 

 with the bifurcation of the main branch in the genotype. It is 

 segmented, for transverse lines that alternate with the whorls are 

 seen in at least one of the specimens [pi. I, fig. 5]. The brandh- 

 lets of the next order are somewhat bulbous at their bases and pro- 

 duce an annulation of the main branch. To some extent the latter 

 is also seen to contract between the whorls [see pi. I, fig. 5]. 

 The branchlets are extremely slender and flaccid and therefore 

 much subjected to current dragging [see pi. 2, fig. 2]. The 

 whorls of the branchlets of higher orders are far apart and consist 

 only of three or four branchlets. On account of their length the 



