Echinoid Radioles, Anuulocidavis. 
147 
even when clear there, it is scarcely to be detected on the handle. Whereas in 
the remiform radioles and in the narrower spatuliformes the striae of the blade 
appear to converge to the handle, and to be continuous throughout, in the wider 
spatuliformes the striae on the wings of the blade are cut off at the margins and 
not continued on the handle. The number of striae to TO mm. is 6 on the outer 
face of specimen j, and the same at the proximal end of the outer face in specimen 
k. In the distal region of the latter, the striae become mere granules. In m the 
striae on the collerette are distinct; those in the proximal region of the shaft are 
less distinct. 
The annulus is distinct, and is curved distalwards in the median line on both 
inner and outer surfaces, but more so on the former, as indicated by the detailed 
measurements. The rim round the acetabulum is also well marked as a rule. 
Except for the very slight concavity occasionally seen on the inner surface 
of the blade, there is no sign of ridges passing from the handle to the distal angles 
of the blade, such as characterise the similar form in A. Buchi. 
Although the handle, as stated, forms an angle with the blade, the ridge at 
the apex of the angle is not raised. In other words there is no depression in the 
handle on the proximal side of the angle-ridge (PI. X, fig. 264). Jt is this feature 
that may be taken to separate the spatuliform from the trulliform radioles. Another 
distinctive character is that in the spatuliformes the distal margin is not excavate 
as it is in the trulliformes. Of course there are specimens that cannot easily be 
assigned to one more than the other, but they are rare. 
3. R a d i o 1 i trulliformes. 
(PI. X, figs. 265—269.) 
From among the 100 specimens of this form found at Jeruzsälemhegy, 19 
lettered a —s are selected for measurement (in millimetres) and outline drawings. 
But in Order that these measurements may be intelligible, it is convenient first to 
give the description of a single well-developed radiole, lettered f. The intermediate 
stages, as represented by a-c, lead one to regard this as modified from the 
spatuliform type by the greater bending of the handle towards the inner surface 
of the blade, resulting in the sharp delimitation of the latter. The handle, instead 
of being like that of an oar or a racquet, is now like the handle of a bricklayer’s 
trowel, in that it springs from the back of the blade at a sharp angle, while the 
base proper again bends round so as to become more nearly parallel to the plane 
of the blade. At the same time the blade assumes a curved hexagonal outline and 
increases in width. These changes are gradual, but the clearly marked forms, such 
as f, are far more numerous than the intermediate ones. The description of f will 
now be given in detail (PI. X, figs. 265, 266). 
The shaft is here clearly divided into blade and handle, the latter being 
continuous with the base proper, which comprises collerette, annulus, and acetabulum. 
The blade is differentiated by a clearly defined margin into an inner and an outer 
face. These correspond in the main to the inner and outer faces of the remiform 
and spatuliform radioles, but are not strictly homologous therewith, since the outer 
face no longer passes down on to the handle, which is entirely transferred to the 
inner face. On the other hand, while the two faces of the handle can still be 
io* 
