50 W. G. RIDEWOOD. 



to suspect that one of them is a parent colony of the others. It is further of 

 interest that, although these colonies appear so young and so recently established, 

 there are present, attached to the interior of the test, numerous solitary eggs 

 of oval shape, small size (averaging '42 by '47 mm.) and pale yellow colour. They 

 are affixed by a short, fine, transparent pedicle continuous with the thin enveloping 

 membrane. 



All the specimens were preserved by being placed in 70 per cent, alcohol. 



Tubarium. 



The tubarium of this species in its present state, after being in alcohol for three 

 years, is of a light brown colour. It is larger than that of Cephalodiscus dodecalophus, 

 has shorter and more closely-set branches, and thicker and longer spines. 



The largest piece (fig. 1, B, plate 2) measures about 110 mm. by 70 mm. The 

 original label accompanying this piece is marked " Has been dry." A smaller piece 

 which was dredged at the same time (fig. 1, A), and which in all probability is part of 

 the same colony, is free from this disadvantage, and does not show the shrivelling of 

 the tips of the spines which is apparent in specimen B (as also in C). 



The cavity occupied by the polypides is continuous throughout, and branches 

 regularly with the branching of the tubarium. In fig. 22, plate 4, is given a 

 diagrammatic representation of the cavity of the tubarium, as though the polypides 

 had been removed, a cast made of the interior, and the tubarium subsequently 

 stripped off. Sections taken through the stems and branches of the colony are roughly 

 elliptical in shape, and measure about 6 by 4 mm. across. The width of the interior 

 of the tube is from 2 to 4 mm., but it is greater where a branch becomes flattened, 

 as it frequently does towards its free extremity. 



The wall of the tube is thinnest in those parts where the test is most regularly 

 tubular, and where there are no spines. The thickness here is not more than 3 mm. 

 In the basal parts of the colony the tubarium is more massive, and in places attains 

 a thickness of 2 or 3 mm. Although the lumen varies in diameter in the manner 

 described in the preceding paragraph, the inner surface of the tubarium is smooth 

 and even, and is not irregularly chambered as it is in C. dodecalophus. There are 

 no internal trabeculae, ridges or partitions ; and the cavity is continuous from one- 

 end of the colony to the other. The rooted end is, of course, blind, but there are 

 several short branches with ostia close around it. 



The terminal branches are short, about 10 to 13 mm. in length, and the portions 

 of the relatively main stem between two consecutive branches are rarely more than 

 10 mm. in length, frequently much less. 



The openings of the tubarium, the ostia, are situated at the terminations of the 

 branches, and are one, two or three in number at the end of each branch. This rule 

 that the openings are terminal is not without exception, but most of the instances of 



