LOVENECHINUS. 333 



broken ends of the two ambulacra on the left, are more than confirmed by a larger specimen 

 of this species in the British Museum (E 3,432) from the Carboniferous Limestone of Llysfaen, 

 near Llandulas [my Plate 36, fig. 6]. This specimen further shows that the adradial suture 

 face of the interambulacrum is denticulate at its outer margin, and faintly grooved over all 

 its surface for the reception of the outer ambulacrals. 



" The interambulacra are closely united to the genital plates by the proximal plates of their 

 admedian columns. Immediately adjoining these plates the proximal plates of the outer 

 columns make their appearance. The area in which most is preserved is the right anterior, 

 which is visible at least as far as the ambitus and possibly further. Throughout the whole 

 of this there is no evidence for more than four columns, although de Koninck's figure shows a 

 fifth coming in. The plates of the outer columns are pentagonal, and about the ambitus attain 

 a width of 7.4 mm. with a height of 5 mm. Those of the admedian columns are hexagonal 

 and, at the same level, have a width of 6.4 mm. and a height of 5.1 mm. The total width of 

 the interambulacrum here is about 22.5 mm. 



"The interambulacrals are covered with miliaries, about four to the square millimeter, 

 showing a slight tendency to be arranged in rows. They bore small radioles of which the 

 remains are seen in the adradial furrows. The plates seem firmly united by vertical sutures. 



"Remains of. minute radioles, with fine longitudinal striation, are preserved in the matrix, 

 especially in the grooves on each side of the ambulacra. 



"The apical system consists of five genitals (or basals) and five oculars (or radials). 



"The five oculars are minute triangular plates, squeezed like wedges between the genitals. 

 They are depressed and bear miliaries like those of the genitals. Having with much trouble 

 removed the matrix, I can now see the outlines of all, except the suture separating the anterior 

 ocular from the left anterior genital. The plates are about 1.4 mm. high and about 0.8 mm. 

 wide at the base, or adoral margin. On none can I detect any trace of an ocular pore, nor are 

 the miliaries arranged round any depression where a pore might lie. Of course these pore- 

 are notoriously difficult to see in all fossil echinoids, so that it does not appear necessary to 

 adopt the alternative view that the ocular tentacle may have emerged between the ocular and 

 the ambulacrum. [I have not seen a pore on the exterior of an ocular plate in any species 

 of this family. R. T. J.] Each ocular lies below the level of the adjacent genitals and bends 

 sharply down to meet the ambulacrum almost at right angles. This gives the impression 

 that the ambulacrum passes beneath the ocular and that the union was flexible; but it is 

 difficult to see clearly into the angle. 



"The genital plates form a closed circlet, with abutting sides about 1.2 mm. long. Four 

 of the genitals are approximately equal in size and form, having a width of about 4 mm., meas- 

 ured from the distal ends of the interbasal sutures, and a height, measured along the interradius, 

 not exceeding 3.5 mm. The outline of these plates is much more pentagonal than heptagonal; 



