40 RECORDS OF THE AUSTRALIAN MUSEUM. 



Pasytlieri qiiadridenfata (Ellis and Solander), var. hajpi, Billard, Arch, de 

 ■ Zool. exp. et gen. (4), vii., 1907, p. 835, fig. vi. A, B. Td., Billard, 

 Ann. Sci. Xat.; Zool. (9), ix., 1909, p. 321. 



Growing upon the surface of a seaweed are numerous colonies whicli 

 do not exceed 6 mm. in height. Typical specimens of Pastjtlieii 

 quadridt'iitntii have the hydrothecae in sets of one, two, or three pairs, 

 each pair in contact with those above and below in the same set. In the 

 specimens which I have referi^ed to Pasijtliea qiiadridentata, var. ohllqua, 

 the majority of the internodes bear only a single pair of hydrothecce each. 

 In this respect the colonies do not differ from a typical Seyiularia, and 

 thus constitute an inteiMuediate link between the typical Fagytliea and the 

 true SertuJaria. Some of the specimens have the same disposition of the 

 hydrothecae on the proximal part of the stem, while at the distal 

 extremity the hydrothecte on the last two internodes are grouped in sets 

 of two each, as in typical specimens of Pasythea quadridevfufd. 



The pi'esent specimens also differ from the typical form in that the 

 apertures of the hydrothecte are directed more to the front and have 

 blunter teeth than in the type, and the joints between the internodes are 

 in some cases simple and inconspicuous, while in others tlie base of the 

 upper internode runs down into a point in fi^ont, and the top of the lower 

 one is produced upwards into a similar point at the back. A similai' 

 articulation sepai'ates the basal portion, which is destitute of hydrothecce, 

 from the remainder of the colony. 



The specimens thus agree most closely with those described and 

 figured bv Billard^^ from Mozambique under the name of Fdsijthed 

 qiiadridenfata, var. halei, and with Bale's figure^-' (pi. xiv., Hg. 6) of a 

 colony fi^om Boiidi, New South Wales. 



The transverse mai^kings in the hydrorhiza, referred to by Warren in 

 his description of Natal specimens of Pa>tythea quadrideutata, are well 

 developed in the present colonies. These markings are very similar to 

 those which occur in Sertularia miviiua, in the fo)'m of ribs of chitin 

 I'unning vertically up the sides of the hydrorhizal tubes at irregular- 

 intervals, and projecting across the cavity of the tube foi- about a quarter 

 of its breadth. Warren has suggested that the occurrence of this 

 structure may be of specific value, but Ritchie has I'ecorded its presence 

 in such widely-separated species as Pndocoryne eclinata, Sertularia 

 heterodoiita, and PI innularia lageiiifera, var. septifera. 

 T)iine)isious. — 



Height of colony ... ... ... ... ... ... up to H nun. 



Stem internode, length O-tO-0-49 nun. 



Stem internode, diameter ... ... ... ()-12-019 mm. 



Hydrotheca, length of external ]>i'ofile .. ... 0-28-0-2!) mm. 



Hydrotheca, length free ... ... ... ... 0-15-0-19 mm. 



Hydrotheca, length adnata ... ... ... ... O-23-0-24 mm. 



Hydrotheca, diameter at mouth ... ... ... 010-012 mm. 



Hydrotheca, diameter at base ... ... ... ... 011-0-12 mm. 



Distance Vietween two pairs of hydrotliecfe ... ... 0'14-0-:U mm. 



'■i Billard— Arch, de Zool. exp. et gon. (4), vii.. 1907, p. 3:^5. fig. 6. 



1^ Bale— Proc. Linn. Soc. N.S.Wales (2), iii., 188S, p. 770, pi. xiv., fig. G. 



