36 
THE VOYAGE OF H.M.S. CHALLENGER. 
aperture, which is more or less triangular or sub-rhomboidal ; the outer angle running into 
the digital process, which is continued from the external angle, and supports on the upper 
side four or five long curved articulated spines. Two long articulated dorsal spines near 
the upper part of the zooecium and a slenderer one near the rachis. No avicularia. The 
median cell at a bifurcation has a triangular aperture, the upper border arched in the 
middle, and no digital process. Ooecium helmet-shaped, with a slightly thickened border. 
Habitat. — Station 196, lat. 0° 48' S., long. 126° 58' E., 825 fathoms, hard ground. 
Brought up in the same haul together with Bicellaria bella and Bicellaria moluccensis, 
the present form is indistinguishable, by the naked eye, from the former of these species, 
and for some time I was inclined to regard it as a variety ; but notwithstanding the several 
points in which they show strong similarity, in all important respects they differ very 
widely. I may add that the comparison has been made with abundance of specimens, and 
the distinction appears to me to rest on ample grounds. 
The chief points of resemblance may be stated to be : — 
1. The general habit, which is precisely the same, including the mode in which the 
numerous spines arch over the front of the branches, though these appendages are less 
numerous in Bicellaria macilenta than in Bicellaria bella. 
2. The outer angle of the aperture is prolonged into the base of the digital process ; 
but in Bicellaria macilenta this prolongation is more extensive. 
3. The curious angular curvatures of what may be termed the rachis, which forms an 
abrupt angle at the base of the body of each zoarium. 
The similarity in form of the ocecia might also be cited ; but as that organ presents 
exactly the same appearance in several other species, it is not a distinctive character of 
any value in the present case. 
The differences are : — 
1. The form of the body of the zooecium, which in Bicellaria macilenta is very much 
narrower and almost cylindrical. 
2. The absence of a digital process in the median zooecium at a bifurcation, whilst in 
Bicellaria bella that, or rather it may be said, the two median zooecia, in the same 
situation, are furnished with a digital process, projecting directly in front, owing to the 
circumstance that the zooecia in question look sideways and not directly in front, as in 
Bicellaria macilenta. 
3. The total absence of avicularia of any kind in Bicellaria macilenta. 
2. Bugula, Oken. 
Bugula , Oken, Busk, Smitt, Gray (sp.), Smitt, Hincks, &c. 
Acamarclm, Lamx., Blainv., d’Orb. (sp.). 
Crisia (sp.), Lamx. 
