cLAKK.] CIDAlilb JSl'LENDENS. 33 



ECHINOIDEA. 



EUECIIIIVOIDEA. 



EEGULARES. 

 CIDARID^. 



Test spheroidal. Ambulacral areas narrow, more or less flexuous, 

 and covered only with very small tubercles, luteraiubiilaeral areas 

 very wide, with two rows of large tubercles that bear the primary 

 sj)iues. The apical disk is composed of five geuital aud five oculai' 

 plates. 



CIDARIS Kleiu emend. Lamarck. 



CiDARIS SPLENDENS MortOU. 



Plate VI, Figs. Sa-fj. 



Cidaris ( ?) sj). Morton, 1829. Philadelphia Acad. Nat. Sci. Jour., Ist scr., vol. 6, p. 12.S. 

 Echinus sj). Morton, 1830. Amer. Jour. Sci., Istser., vol. 17, p. 287; vol. 18, I'l. in, 



Fi<--8. 12, 13. 

 Cidarites splcndens^ Morton, 18-11. Philadelphia Acad. Nat. Sci. Proc, vol. 1, p. 132. 

 Cidarites arm'ujer Morton, 1842. Philadelphia Acad. Nat. Sci. Jour., 1st scr., vol. 8, 



p. 215, PI. II, Fig. 1. 

 Cidaris armi(jer Gabb, 1859. Cat. luvert. Fossils, Cretaceous Formation, p. 18. 

 Cidaris sjjlendcus Gabb, 1859. Cat. Invert. Fossils, Cretaceous Fonnation, p. 18. 

 Cidaris armiger Clark, 1891. Johns Hopkins University Circulars, No.87, p. 75. 



Deierminntive characters. — Test of moderate size, spheroidal. Ambu- 

 lacral areas narrow, flexuoUs, with four rows of granules between the 

 pore pairs, the outer rows larger than the inner; imperfectly defined 

 granules also appear between the pores of each pair. Interambulacral 

 areas very wide, with seven or eight plates in each column, each plate 

 bearing a tubercle of large size, that is characterized by a wide circular 

 areola, smooth boss, and small perforated mamelon. Miliary area 

 small and covered with numerous thickly- set granules of small size. 

 Sutures sharply defined, depressed. Spines elongated, cylindrical, 

 with longitudinal rows of sharp denticulated processes. 



Dimensions. — Height, § inch; width. If inches. 



Description. — The first mention of this form is made by Morton in 

 1829, when he doubtfully referred a few fragments to (Maris without 

 an attempt at specific determination. Several of the more important 

 characters were then given, but as the material examined included only 

 detached plates and a few spines tlie description necessarily lacked 

 much of completeness. In 1841 Morton proposed the name Cidarites 

 8l)Undens and then more accurately defined the species. In 1842 he 

 redescribed and now for the first tim(> figured the same form as (Jidar' 



' Mortou doubtless iutcnilecl to use the term s])lcndens iuaUwA of splendcun, which is iiroh;il)ly a typo- 

 graphical error. In the publication of 1842, where ann'njer is substituted, the form gplendciis is used. 



Bull. 97 3 



