36 MESOZOIC ECHINODERMATA OF THE UNITED STATES. [bull. 97. 



CiDARis CALiFORNicus Clark. 



Plate VI, Figs. la-b. 



Determinative characters. — Test iiiiknowu. Spines large, club-shaped, 

 with rows of large granules that coalesce to form longitudinal ridges 

 which extend from neck to point of spine. 



Dimensions. — Spine: length, § inch; breadth in thickest part, f^j inch. 



Description. — Tliis species is based upon detached spines, four or 

 five specimens of which are afforded in material from Taylorsville, 

 California. They are distinctive in every way, and can not be mis- 

 taken, even in fragments. The specimens examined occur as casts, but 

 so well preserved that impressions in gutta-percha, from Avhich the 

 drawings were made, show the characters completely. Each spine has 

 a short narrow neck, beyond which it rapidly increases in size so as to 

 give a club-shaped outline to the middle and upper portions. Eows of 

 longitudinal granules cover the surface from the neck to the point of 

 the spine, presenting the appearance of long serrated ridges (PI. vi, 

 Figs. la-h). 



Related forms. — Separated from C. taylorensis by its club-shaped 

 form and surface characters. 



Locality and geological horizon. — This species is found in Jurassic 

 strata at Taylorsville, California. 



Collection. — U. S. National Museum. 



CiDARis TEXANUS Clark. 

 Plate VII, Figs. la-e. 

 Cidaris tixanus Clark, 1891. Johns Hopkius University Circulars, No. 87, p. 75. 



Determinative characters. — Test large, inflated; Ambulacral areas 

 narrow, sinuous, with four rows of granules between the poriferous 

 avenues, which at the ambitus are increased to six and toward the apical 

 disk and mouth opening are reduced to two rows. Pores oval, sepa- 

 rated by transverse elevations, which partially envelop the openings. 

 Interambulacral areas wide, with large circular tubercles. Areola cir- 

 cular, depressed; boss smooth; manielon small, p ^^'"-rated. Miliary 

 space wide, covered with numerous small granules. '^^ 



Dimensions. — Height, 1^ inches; width, 2^ inches. 



Description. — A large portion of the test of this beautiful species is 

 in an excellent state of preservation. All of the characteristic features, 

 with the exception of those relating to the apical disk and mouth edges, 

 are clearly shoAvn. The test, however, is somewhat compressed, so 

 that the original form can not be with certainty made out. The am- 

 bulacral areas are narrow and slightly flexuous. Between the i)orifer- 

 ous avenues, which are narrow and depressed, are four rows of granules 

 of nearly equal size which directly at the ambitus are increased to six, 



