bth Balanocrinus. - 401 
The series of pits bordering the floors explain the incised 
lines sometimes seen in this position on the weathered fossils, 
e. g., 57542 d. The looser stereom of the floors being more 
readily weathered, these tracts are often deeper in the fossils 
than they can have been in life. Sometimes advanced 
weathering or decomposition emphasizes this greatly (57551 a) 
and also brings out the weak structure of the stereom under 
the radial canal; in decomposing pyritized specimens the 
columnals break into pentameres along the radial planes, 
though in crushed specimens (e. g., 57542a) the cracks 
usually follow the lines of interradial weakness. Thus is 
brought out here, as in B. didactylus, the difference between 
the original pentamerism and the secondary concentration of 
the stroma fibres along interradial pillars. 
Between the Jsocrinus and Balanocrinus types of normal 
joint-face there seems to be every possible gradation. There 
are uo grounds for supposing that the material comprises 
two species, and consequently it cannot comprise two 
genera. 
The Syzygial Joint-face of an Epizygal is well shown in 
57543 ¢ (cf. W. H. Baily’s drawing in Forbes, pl. iv. fig. 8, 
which, for all its inexactness, gives the general appearance 
well). There are 2 facets; diameter parallel to a line 
joining the facets 5°5 mm.; diameter at right angles to this 
5°O mm. Corresponding with the facets the radial tracts 
are raised, as in B. didactylus, though not quite so markedly. 
Peripheral crenellae about 7, broadening outwards and 
confluent ; length on the interradius ‘2 mm., gradually 
increasing to 1:0 mm., but these long ones die away into the 
floor. Radial ridge-groups comprise about 3 pairs of 
reduced obscure crenellae, rapidly decreasing in size towards 
the centre, and tending to le at right angles to the radial 
canal; this last is little more than a fine line, and is bordered 
by no raised ridges. Petal-floors flush. 
The Hypozygal joint-faces are not clear ; apparently they 
correspond, mutatis mutandis, to the epizygal face, but are 
not so strongly marked. One of the clearest is in 57543 6. 
The Transverse Section of the stem is generally sub- 
cylindrical, usually varying towards either pentagonal or 
quinguelobate, as in all figures of Sowerby and Forbes. 
The specimens seen by J. S. Miller were no doubt sub- 
pentagonal—hence the name subbasaltiformis. Those in 
J. Woodward’s collection were probably subcylindrical, like 
other Entrocho-Asteriae. Quinquelobation may occasionally 
be, marked, but no specimen can be called stellate, though 
that condition is approached by 57541 and E 21926. 
Ann. & Mag. N. Hist. Ser. 8. Vol. xx. 27 
