PENNATTTLIDA DREDGED BY H.M.S. "TRITON." 123 



From these figures it will be seen that specimens A and B approach very 

 closely Kolliker's variety angustifolia. 



P. phosphorea var. aculeata, KolL (PL XXI. figs. 4-7, and PL XXII. figs. 8-16.) 



This very well-marked variety, which does not appear to have been hitherto 

 recorded from British seas, is characterised by the long and slender shape of 

 the leaves (PL XXI. figs. 4 and 5), the small number of their component 

 polyps, their distance apart, and the extent to which they are separate from one 

 another ; and above <all, by the fact that a number of the zooids of the ventral 

 surface (figs. 4 and 5,f) are very exceptionally developed — assuming the form 

 of conical spines, which project from the rachis for a distance in some speci- 

 mens of 3" 5 mm., or even more. 



This variety was first described in 1858 by Koren and Danielssen,* who 

 found it at a single locality near Christiansund, where it occurred rather 

 abundantly on clay bottom at the depth of 80 to 100 fathoms. Since then it 

 has been taken by Sars at Christiansund at a depth of 30 to 70 fathoms, and 

 in the Throndhjemsfjord in 100 fathoms water; by Carpenter and Wyville 

 Thomson, during the "Porcupine " expedition in the Atlantic Ocean, 48° 26' N., 

 9° 44' W., at a depth of 358 fathoms ; and by Whiteaves in the Gulf of St 

 Lawrence, at a depth of 160 to 200 fathoms. 



Of the " Triton " specimens of P. phosphorea, all those, 19 in number, 

 obtained at Station 11, depth 555 fathoms, belong to this variety, as also does the 

 single specimen from the " Knight Errant" collection dredged at Station 7, in 530 

 fathoms water. As the variety is a very interesting one, and has not yet been 

 satisfactorily described, I have taken the opportunity afforded by the large number 

 of specimens available to investigate in some detail the more important structural 

 details, directing my attention more particularly to the large ventral zooids. 



The following table gives the measurements of the single specimen from the 

 " Knight Errant " and of two of the " Triton " specimens. All the latter are of 

 small size, the specimen B being one of the largest. 





A. 



B. 



C. 





" Knight Errant " 

 Collection. 



" Triton ' 



Collection. 



Length of colony, 



70 mm. 



62 mm. 



48 mm 



„ racbis, 



31 



28-5 



24 



,, stalk, 



39 



33-5 



24 



„ leaves (longest), 



12 



13 



10 



Greatest width of leaves, 



3 



1-5 



1-5 



Number of pairs of leaves, 



19 



14 



10 



Number of polyps per leaf, 



9 



6 



7 



Length of largest zooids, 



3 



3-5 



3 



* Koren and Danielssen, Forhandlinger i. Videnskabsselskabet i. Christiania, p. 25, 1858; also 

 Fauna Littorulis Norvegiw, part iii. pp. 86-88, and pi. ii. figs. 8 and 9, Bergen, 1877. 



