190 PROFESSOR J. ARTHUR THOMSON ON THE 



In four of the specimens the total length of the stem was found to be 18 '5, 17, 

 16'5, and 16'5 cm. Three of the four had ten branches on each side, while the 

 longest specimen had twelve branches on one side and thirteen on the other. The 

 branches occur in pairs with such strict uniformity that one might suspect the loss 

 of a branch. But there is no hint of this. 



The branches on one specimen were measured, and the lengths in centimetres 

 from the base upward are given in the following Table : 



Right Side. Left Side. 



Branoli . Length in cm. Length in cm. 



1 2-4 2-5 



2 Broken off. 2 '5 



3 5-2 3-5 



4 6-8 4-7 



5 7-6 5-5 



6 7-6 6-0 



7 8-5 6-5 



8 7-5 6-5 



9 5-6 6-3 

 10 4-7 4-0 



Thus, on one side, branch 7 is longest ; on the other, branches 7 and 8 are of equal 

 length. The lower and higher branches are shorter than the more central, and the 

 gradation of the graceful colony is on the whole regular. 



" Isolated " zooids occur both on the main stem and on the branches ; they are 

 disposed on only one side of the branches, at fairly regular intervals ; their bases are 

 connected by ccenenchymatous outgrowths. They correspond to the Bathypathes-type. 



The axis of the stem and branches is dark brown in colour when looked at with 

 the naked eye. The spines, broad at the base, and tapering to a point, arise at right 

 angles to the axis, and four longitudinal rows are visible from one aspect. The move- 

 ment of the gas and liquid within the axis showed that it was hollow, as cross sections 

 confirmed. 



The specimens agree well with the description which BROOK gave of Bathypathes 

 patula, var. plenispina, e.g. as to the acute angle between the lower branches and 

 the four rows of spines visible from one aspect. But it may be noted that the 

 Challenger specimen was only 12 centimetres in length, and had only three pairs 

 of branches. The type specimen of B. patula had, however, 9-11 branches. 



The jar containing the specimens is labelled Burdwood Bank, 1st December 1903, 

 54 25' S., 57 32' W., 56 fathoms. 



2. Bathypathes alternata, Brook. 



A fine and well-preserved specimen, measuring 24 cm. in height by 18 cm. in 

 breadth across the lowest branches, seems referable to Bathypathes alternata, of which 

 the Challenger Expedition also obtained but a single example. Of the total height, 

 10 cm. go to the sterile part and 14 cm. to the pinnate frond. 



(ROY. PHYS. soc. OP EDIN. PHOC., VOL. xvi.) 



