KONINCKOCIDARIS. 285 



Koninckocidaris cotteaui Dollo and Buisscret. 



Koninckocidaris cotteaui Dollo and Buisseret, 1888, p. 959. 

 Perisckodom.ua [cotteaui] Tornquist, 1897, p. 725. 

 Lepidechinus cotteaui Lambert and Thiery, 1910, p. 122. 



Known from a fragment of a test and isolated plates. General form unknown, but proba- 

 bly it was spheroidal as is K. silurica. Apical disc and jaws unknown. Ambulacral plates 

 high, two about equaling the height of an adambulacral plate; pore-pairs lie near the next 

 adjacent interambulacrum, two pores to each plate, not on a line, but one higher than the 

 other. Dollo and Buisseret say that the pore nearer the middle of the area is higher up. This 

 is opposed to what I have found in all Palaeozoic species, and probably they had their fragment 

 incorrectly oriented. If we change the orientation, then it would read, pore nearer the middle of 

 the area lower, which is in accord with what I find in Palaeozoic and most modern Echini (p. 57). 

 Ambulacral plates bear numerous secondary tubercles, similar to those on the interambulacra. 

 Interambulacra with seven columns of plates, the central column narrower, plates polygonal, 

 strongly imbricating, and ornamented with secondary tubercles; the adambulacral plates bear 

 in addition marginally a primary perforate tubercle. Described from a single specimen, which 

 has not been figured. 



Lower Carboniferous, Belgium. 



'Koninckocidaris silurica sp. nov. 

 Plate 19, fig. 1; Plate 20, figs. 5, 6. 



It was with keen delight that I received this most interesting fossil which Professor H. L. 

 Fairchild most kindly sent me for study. It occurs in the Niagara Limestone, Silurian, and 

 therefore is much earlier geologically than any American echinoid previously known. It also 

 adds much to our knowledge of this very interesting ancient genus. The specimen is an internal 

 view and the plates are beautifully preserved, but one must bear in mind that as it is internal, 

 therefore the direction of imbrication is opposite to what it would be if the specimen were 

 viewed from the exterior (compare text-figs. 32-38, p. 75). 



Test high, spheroidal, as gathered from the dorsal portion, which alone is preserved. The 

 lower part of the specimen is probably at or near the plane of the mid-zone. Height of specimen 

 52 mm., width of ambulacrum J at the lower portion 9 mm.; width of the interambulacrum on 

 same line about 43 mm. From these figures the circumference would be about 260 mm. and 

 the diameter in the neighborhood of 83 mm. Ambulacra rather wide, much wider than they 

 would be on the exterior, on account of the lateral beveling of ambulacral plates under (but 

 here over) the adradials. Pore-pairs relatively near the ventral part of each plate, and near 

 the middle of the area, largely due to its being an internal view (compare Plate 20, figs. 9, 10). 

 Ambulacral plates are high, about three equaling the height of an adambulacral plate; in this 



