BUGULA GRACILIS. 87 



for this species ; but I have a specimen in my collection 

 which was obtained on our coasts, and which I had 

 wrongly referred to B. plumosa, until the examination of 

 fine examples of the same form from the United States 

 directed my special attention to it. 



Geographical Distribution. Madeira (J. Y. J.) : 

 Lynn, Massachusetts (Eev. W. Hincks). 



A reference to Mr. Busk's description of this species 

 in the ' Microscopical Journal ' will show that it differs 

 in several important points from the one given above. I 

 should hardly have felt justified in assuming the identity 

 of B. gracilis and the present form (which I shall distin- 

 guish as B, gracilis, var. uncinata), had not Mr. Busk 

 stated that his specimen of the former was a small one, 

 so small indeed (it is implied) as to render it difficult to 

 determine the habit satisfactorily. 



The general character of the zooecium is undoubtedly 

 the same in both ; but B. gracilis, Busk, is represented as 

 having only two spines, whilst its aperture is described as 

 not extending below the middle of the cell. At the same 

 time there is no mention in Busk's diagnosis of the 

 remarkable appendages which are present on every shoot 

 of the var. uncinata, in both the British and North- 

 American examples. 



As to these differences, it may be remarked that the 

 spine or denticle on the outer angular extremity of the 

 aperture is rather inconspicuous, and might easily be 

 overlooked, especially in dried specimens, and that the 

 aperture may not improbably vary in length. With 

 respect to the appendages, on a fragmentary specimen 

 they might not be present; or it is possible that they 

 may only be developed under certain local conditions. 

 Looking to the great general similarity of the two forms. 



