ECHINODERMATA—ECHINOIDEA. 



587 



primary tubercles resembling those of the ambulacra but larger. 



Secondary tubercles and granules surrounding the areolas. Spines 



long, hollow, longitudinally striated. Mouth large, polygonal. 



Jurassic-Recent. 



20. D. (Pseudodiadema) texanum (Roemer). (Fig. 1920.) 



Comanchic. 

 Small, depressed. Sides inflated. Upper and lower surfaces 



Fig. 1920. Diadema {Pseudodiadema) texanum. a, upper surface ; b, side view ; 

 c, lower surface ; d^ ambulacra! area enlarged. (After Clark.) 



equally flattened. Pores in a single series. Peristome wide ; peri- 

 proct subcircular, with deep cut in right anterior ambulacrum. 

 Fredericksburg of Texas. 



XIII. DiPLOPODiA McCoy. 



Differs from Diadema in having the pairs of pores in double 

 vertical rows near the center of top and bottom of test and single 

 at the ambitus. Jurassic and Cretacic. 

 21. D. texana (Roemer). (Cyphosoma texanum.) (Fig. 192 1, 



a^d.) Comanchic. 



Large, with inflated sides. Lower surface concave. Pores in 

 single pairs from mouth to ambitus (except immediately border- 

 ing the mouth) beyond which to the apex they are in double rows. 

 Periproct large, subpentagonal. 



Comanche-Peak (Fredericksburgian) of Texas. 



XIV. Pedinopsis Cotteau. 



Differs from Diplopodia in having more than one tubercle on 

 ambulacral plate, and numerous smaller tubercles on interambu- 



