SUB-CI 



EUECHINOIDEA CIDAROIDA 



225 



(c) Lciocidaris, Desor. Like the preceding, l>nt with uncrenulated tubercles. Spines large, 

 smooth, cylindrical. Cretaceous to Recent. 



(d) Dorocidaris, A. Ag. Like ('i,l,i,-is, but with smooth tubercles. Recent. 



(e) Stephanocidaris, A. Ag. Test thin : apieal system larger than the peristome, the plates 

 feebly united, and the whole flexible. Recent. 



(/) Phyllacanthus, Brandt. Test large, swollen, and with eight to eleven IAmb plates. Afnb 

 pores in a broad zone, conjugated. Primary tubercles large, smooth, perforate. Recent. 



(if) Poi'ociilnri*. I -".til). Amb broad and straight ; pores wide apart, conjugated. 



Primary tubercles perforate and crenulate. Scrobicules transversely oval, with shallow grooves 

 radiating from the periphery toward 

 the centre, with or without pores at \ A 



the outer extremity of the grooves. 

 Tertiary and Recent. 



(ft) Gfoniocidarii) Desor. Test hi^h. 

 with numerous coronal plates, and 

 narrow Amb. The median sutural 

 regions of both areas are sunken, form- 

 ing with the horizontal sutures a zig/ag, 

 with pit-like depressions at the angles. 

 Recent. 



Orthocidaris, Cott. Apical 

 system small, pentagonal. Amb 

 narrow, straight ; pairs of pores 

 in simple straight series, the 

 d^roarated by a granule. 

 / M M rv broad, numerously 

 plaft(PPrimary tubercles small, 

 plain, perforate, and distant. 

 Lower Cretaceous ; Europe. pio yQ 



Temmcidaris, Cott. Upper RhaMocid , iris ^Or^nyana, Desor. 



OretaceOUS. PolmidariS, Ouenst. u PP er Jura : Kelheim-Winzer, Bavaria. 



TT T -A, Fragment of test, i/!. B, Ami plates, 



Upper Jura. enlarged. 



SECTION B. AMBULACRAL PAIRS 

 OF PORES BISERIAL. 



Diplocidaris, Desor. Test 

 large, spheroidal. Amb narrow, 

 straight ; poriferous interporifer- 

 ous zones of equal width. Pairs 

 of pores very numerous, close, 

 alternating more or less. IAmb 

 broad, with seven to eight plates 

 in each column. Primary tubercles 

 large, perforate, scrobiculate. 

 Upper Jura ; Europe. 



Tetracidaris, Cott. (Fig. 362) 

 Remarkable in having four Forocidaris SM , eli> Goldf Nummu . 



Coronal plates in each IAmb at litic Limestone; Mokkatam, near Cairo. 



the ambitus, but diminishing to ' d Bpine ' 



two at the apex. [It should be noticed, however, that A. Agassiz has observed 

 a somewhat similar division in the IAmb plates of the recent genus Astropyga 1 

 Amb straight, moderately broad. Poriferous zones depressed, pairs incom- 

 pletely biserial ; interporiferous areas narrow, granular, with a row of plain 



VOL. I 



FIG. 361. 

 Porociclaris Schmieileli, Goldf. Nummu- 



FIG. 360. 



Rhabdocitlaris 

 horrida, Merian. 

 Middle Jura. 

 Spine, l/i- 



