2 PROFESSOR J. A. THOMSON AND MR JAMES RITCHIE 



throughout its course, and gives off many branches which are also naked. The 

 branches arise at various acute angles, and some of them, especially towards the 

 lower end, are almost as thick (1'5 mm.) as the main stem (1'75 mm. at the lowest 

 part). Like the latter, they give origin to smaller branches, which may bear minute 

 twigs with a single joint or with two joints. Small branches with only a few joints 

 are much more frequent on the stem than the large branches already mentioned, 

 and they stand off from the stem at greater angles than the large branches some, 

 indeed, arising perpendicularly. 



All the branches spring from the calcareous internodes, and are equally developed 

 on all sides. They vary in number from 3 to 7, or even 8, per joint, 7 perhaps being 

 the most common number. They seem to arise quite irregularly, a frequent interval 

 between two on the same side being 4 mm. ; but very occasionally 3 or 4 arise in 

 a whorl. 



The axis consists of alternate horny nodes and calcareous internodes, the latter 

 being covered with very fine longitudinal grooves. The internodes are much longer 

 than the nodes, and are themselves longer towards the apex of the colony. The 

 following measurements of successive internodes were taken : (a) from the lowest 

 joint upwards, 5, 6'5, 7, 9 mm. ; (b) from the topmost joint downwards, 9, 9'5, 10, 9, 

 10 mm. Near the base the horny nodes are only about 0'5 mm. in length, and 

 gradually decrease towards the apex. The branches never begin with a horny node ; 

 in every case a process arises from the originative calcareous node, and on this the 

 first horny node of the branch is based. 



This species most closely approaches P. antarctica ; but the branches arise from all 

 surfaces of the stem and secondary branches, and are equally developed on all sides, 

 whereas in P. antarctica the branches arise from only four sides and are unequally 

 developed. Moreover, in the new species the calcareous internodes are much longer 

 than in P. antarctica, and may bear 7 or 8 branches, whereas in P. antarctica there 

 are only about 4 per joint. 



The specimen bears several siliceous sponges, several Polyzoa, a small brown 

 Actinian, and several worm-tubes. 



Locality. Station 411, lat. 74 l' S.,long. 22 W.; 161 fathoms. Surface tempera- 

 ture 28'9, March 12, 1904. 



Family PRIMNOID^. 



Sub-family PRIMNOIN^E. 

 Thouarettalrucei, n. sp., PI. I. fig. 1 ; PI. II. fig. 1. 



Several specimens of strong upright branched colonies of a creamy-white colour 

 were found at various stations. The largest specimen is a bushy colony 14 cm. in 

 height by 10'5 cm. in maximum breadth, with an axis 5 mm. in breadth at the base ; 



(ROY. soc. EDIN. TRANS., VOL. xi>i., 852.) 



