404 CELLEPORIDE. 



Var. a {attenuata. Alder). Zoarium slender and of uni- 

 form thickness throughout. Zocecia less ventricose and 

 crowded, and the surface consequently smoother and 

 more even ; avicularia more sparingly developed. 



Habitat. On zoophytes, chiefly from deep water. 



Localities. Off" Polperro, 30 fathoms (T. H.) : North- 

 umberland, not uncommon (Alder) : St. Andrews, on zoo- 

 phytes, abundant and fine (Dr. M'^Intosh) : Wick and Peter- 

 head (C. W. P.) : Shetland, 40-70 fathoms; the Minch 

 (A. M. N.) : Oban; Ireland (T. II.). Yar. a {attenuata). 

 Shetland (Barlee) : ibid., 'Mocal, 80-110 fathoms, 20-25 

 miles N.N.E. of Unst '' (A. M. N.). 



Geographical Distribution. Florida, 9-111 fathoms 

 (Pourtales) . 



In its smaller and more delicate form the habit of this 

 species is very characteristic. It is at once recognizable 

 by the simplicity of its dichotomous branching and the 

 comparative smoothness of its surface. The stem, attenu- 

 ated below, expands gradually upwards, and divides into 

 two principal branches, which are bifurcate at the top. 

 The ramification is commonly carried no further in this 

 variety. The branches are slender, subcylindrical, and 

 taper slightly towards the extremity 5 and the habit is es- 

 sentially neat and compact. This is the form which com- 

 monly occurs on our south-western coasts. 



But in northern examples C. dichotoma presents a very 

 different character. It becomes irregular and rugged in 

 its mode of growth ; the ramification is more complex ; the 

 branches are often broad and spreading ; and the species 

 imitates to a large extent the habit of C. ramulosa. Oc- 

 casionally the branches are much produced, forming 

 tall, cylindrical and slender shoots ; but in this form, 

 as in the one last described, there is a total absence 



