86 BICELLARIIDiE. 



The radical fibres are thin and membranaceous, and form 

 a dense and tangled mass at the base of the shoots. 



I have not been able to give many localities for B. 

 plumosa ; for the species was commonly confounded with 

 B. purpurotinda until Mr. Alder pointed out and defined 

 the differences between them, and it is difficult to decide 

 in many cases which of the two is intended. I have 

 recorded none about which there could be any doubt. 



BuGULA GRACILIS, Busk, var. UNCI N ATA, Hincks. 

 Plate XV. figs. 1-4 ; Pate XII. figs. 6, 7. 

 BuGULA GRACILIS, ^jteVfc, Quart. Journ. Micr. Sc. vi. 125, pi. xix. fig. 1. 



Zoarium composed of many slender shoots, about one inch 



in height, united so as to form bushy tufts, of a pale 



horn-colour when diy ; branches flabellate, somewhat 



spirally disposed, crowded, dichotomously divided into 



narrow segments, longest in the middle of the shoot 



and diminishing above and below. Zooecia biserial and 



alternate, elongate, narrowing slightly downwards, 



with two spines on the outer side above, one of them on 



the free angular extremity of the aperture, and one 



(the longer) behind it, and one on the inner and upper 



angle; aj)erture rather narrow, occupying two thirds 



of the length of the cell or more, somewhat contracted 



below, turned inwards towards the median line. Avicu- 



laria small, placed on the outer margin, a little below 



the top of the aperture. Uncinate prehensile appendages 



distributed in considerable numbers over the dorsal 



surface, and replacing the ordinary radical tubes. 



Ooecia (?). 



Habitat. Unknown. 



Localities. I am unable to give any British locality 



