ECHINODERMA TA—ECHINOIDEA . S7S 



areola (Fig. 1913) ; its outer limit is generally marked by a ring of 

 granules {scrobiciUar circle). All tubercles bear movable spines. 



Fascioles are narrow bands of close granular ornamentation 

 which support many small spines. The peripetalous fasciole fol- 

 lows the margin of the petaloid parts of the ambulacra (Fig. 191 1, 

 A, B, pf; Fig. 1934, g). The a^tal fasciole surrounds the anus, and 

 the subanal fasciole encloses a space beneath the anus. 



The vertical range of the modern echinoids is from low water, 

 where they are sometimes uncovered, to great depths (nearly 

 3,000 fathoms). The larvae lead a meroplanktonic existence. In 

 time echinoids range from the Ordovicic to the present, the division 

 of Palseechinoidea, however, becoming extinct with, or shortly 

 after the end of the Palaeozoic. 



Echinoidea were divided by Zittel and Bronn into Pal^echi- 

 NOIDEA and EuECHiNOiDEA. The former contains three orders: 

 (i) Cystocidaroida with the genus Echinocystites; (2) Bothrio- 

 ciDAROiDA with the genus Bothriocidaris, and (3) Perischo- 

 ECHiNOiDA which comprises the remainder of the Palaeozoic echi- 

 noids. The Euechinoidea are divided by Duncan, into the orders : 

 (i) Cidaroida; (2) Diadem ATOiDA ; (3) Holectypoida ; (4) 

 Clypeastroida, and (5) Spatangoida. 



Literature. 

 1893. Clark, \A^. B. Mesozoic Echinodermata of the U. S., U. S. 



G. S. Bull. 97. 

 1896. Jackson, R. T. Studies of Melonites multiporus (with T. A. 



Jaggar, Jr.), and Studies of Palaeechinoidea. Bull. Geol. See. 



Am., vol. 7, pp. 171-254, pis. 2-9. 

 1899. Merriam, John C. The Tertiary Sea-Urchins of Middle 



California. Cal. Acad. Sci. Proc, 3d ser. , Geol., vol. i, pp. 161- 



170, pis. 21 and 22. 

 1904. Klem, Mary J. A revision of the Palaeozoic Palaeechinoidea, 



with a Synopsis of all known Species. Transactions of the Academy 



of Science of St. Louis, vol. 14, pp. 1-98, pis. L-VL (with complete 



bibliography). 



1908. Weaver, Ch. New Echinoids, from the Tertiary of California. 

 Univ. Cal. Publication. Bull. Dep. Geol., Vol. V., p. 271. 



1909. Pack, R. ^A^. Notes on Echinoids from the Tertiary of Cali- 

 fornia. Ibid., pp. 275-283. 



1909. Slocum, Arthur Ware. New Echinoids from the Ripley 



