ARCHAEOCIDARIS. 281 



stout, and strongly swollen in the middle. The milled ring is weakly defined, shaft smooth 

 for about the lower third, above which it is ornamented with numerous elevated nodose spinules 

 arranged in quite definite parallel series, of which, judging from the figures, there must be about 

 14 vertical series on a spine. 



Productus Limestone, Permian, Katta, Golawali, Chidru, and Bazarwan, India. 



Archaeocidaris spinoclavata Worthen and Miller. 

 Plate 15, figs. 7a-7h. 



Archaeocidaris (?) sp. undet. Meek and Worthen, 1873, Plate 24, figs. 13a-13c. 



Archaeocidaris spinoclavatus Worthen and Miller, 1883, p. 327, Plate 30, figs. 14a-14e; Keyes, 1895, 



p. 190; Klem, 1904, p. 57. 

 Archaeocidaris spinoclavata Miller, 1889, p. 225; Lambert and ThieYy, 1910, p. 124. 



Known only from dissociated interambulacral plates and primary spines. Interambulacral 

 plates hexagonal, wider than high, with a nodose rim around the margin, the expression of 

 secondary tubercles. The basal terrace is not shown, and the details of the surface are doubtful 

 in Worthen and Miller's figures, but, as they say, the specimens are highly silicified and external 

 markings thereby obscured. Primary spines long, or short, circular in section, contracted 

 above the milled ring, beyond which very soon, or at a considerable distance, the spine expands 

 to a marked degree. If it expands quickly, the spine appears highly swollen, as in Plate 15, 

 figs. 7g, 7h, or this may be much less marked, as in fig. 7f, or the greatest expansion may be 

 near the tip of the spine, as in fig. 7e. Proximally the spine is smooth for a short distance, 

 above which it is thickly clothed with nodose spinules. This species is more variable in the 

 form of the spines than other species of the genus yet known. 



Middle and Lower Coal Measures, St. Clair and Marshall Counties, Illinois. Cotypes are 

 stated as in the Illinois State Collection 2,404. 



Archaeocidaris sp. b. Girty. 



Archaeocidaris sp. b. Girty, 1908, p. 110, Plate 27, figs. 18, 18a. 

 Archaeocidaris sp. b. var. The same, p. 111. 

 Archaeocidaris sp. c. The same, p. 111. 

 Archaeocidaris sp. d. The same, p. 111. 



Most fragmentary, based on two pieces of spines which Girty thinks resemble A. spino- 

 clavata, and yet are different, so I insert the record at this place pending further knowledge, 

 should such be attained. The piece representing the distal end expands rapidly into an almost 

 knob-like tip, which, with the shaft, Girty says, appears to be ornamented with short spinules. 

 The shaft is about 0.75 mm., and the expanded distal tip about 2 mm. in diameter. To recog- 

 nize a varietal form of a species which itself is so shadowy that Girty gives it no name, does seem 



