440 Herbert L. Hawkins — Studies on the Echinoidea. 



but such an arrangement would be in keeping with tbe Clypeastroid 

 character. But it might well have reclined upon the " platform " 

 of tbe false ridge, bridging across the concavity between that and the 

 peristome margin, and leaving space for the buccal plates to be 

 retracted behind it. Such speculations are, however, of little value 

 until more is known of the structure of the pyramids. 



4. The Lantern. 



When the chalk infilling of a test of Conulus albogalerus is brushed 

 down, it proves to be surprisingly full of small, usually fragmentary, 

 pieces of calcite. These are naturally often portions of Foraniinifera, 

 Polyzoa, or Pelecypod prisms that have drifted in with the ooze. 

 But the fact remains that these fragments seem more thickly 

 scattered through the internal than the external matrices. I have 

 destroyed several hundreds of specimens of C. albogalerus in my 

 hitherto vain endeavours to find the jaws ; and in one example only, 

 from the top of the If. coranguinum zone near Kingsclere, have 

 any reasonably satisfactory portions been observed. Their nature 

 explains the peristent way in which they elude recognition. They 

 are small, and so delicate in texture that they are translucent, and 

 the friction due to even a soft tooth-brush readily shatters them, if 

 applied at random. In the specimen here noted the chalk within 

 the test was almost powdery in consistency, and was removed with 

 a camel's-hair brush. Two or free fragments, which seem to 

 represent pyramids, were extracted, but they are so broken and 

 difficult to orientate that I prefer to postpone full description of 

 them in the hope of procuring better specimens. 



I have selected one of the fragments (3 mm. long and about 1 mm. 

 broad) as indicative of the general characters of these interesting 

 ossicles. It is shown on PI. XXVIII, Pigs. 4, a, b, c, from three 

 points of view, a, b, and c. How far its outlines are natural or are 

 the product of fracture is difficult to determine. The fragment is 

 roughly triangular, and excessively thin. The top and bottom are 

 both broken. One side is gently crescentic in shape, and the other 

 almost straight. I believe that the curved side is a natural margin, 

 but whether the straight edge is natural or the result of cleavage 

 I cannot determine. One surface (a) shows a carina passing longi- 

 tudinally near to the straight margin at the broader end of the 

 surface, and separating two ovoid excavations. Towards the narrower 

 end the ossicle is thicker, the carina less prominent, and one side of 

 the surface is gently bevelled. A comparison of this figure with that 

 of the alveolar view of a maxilla of Biscoides (Geol. Mag., 1909, 

 PI. VI, Fig. 5) shows an almost startling resemblance. If the 

 straight edge of the Conulus -ossicle is taken to be a cleavage line, 

 cutting the maxilla vertically and removing the inward extension of 

 the inter-pyramidal joint-face, the likeness between the figures is 

 complete in all save proportions. The two figures are supposed to 

 be similarly orientated. 



Fig. b is a view of the (?) cleavage margin of the ossicle. It 

 shows the extreme tenuity of the structure at the broad, excavate 

 end, and its superior massiveness at the narrow end. 



