18 FOSSIL ECHINI OF THE WEST INDIES. 



pits occupy a position at the admedian apex of each interambulacral plate, 

 so that in each plate there are 3 pits, one in the middle line and one at the 

 point of both its upper and lower margins where it comes in contact with the 

 borders of the next adjacent interambulacral plates. 



Height of the test 34 mm., diameter 54 mm., diameter of the periproct 

 and peristome about 15 mm. 



This species is entirely distinct from any other known cidarid occur- 

 ring either fossil or living in the West Indies. It is characterized by 

 the size of the test, which is larger than any other fossil species at 

 present known (though the test of Cidaris peloria, which is unknown, 

 was probably even larger), by the very broad poriferous areas with 

 deep connecting furrows, by the deeply channeled interporiferous 

 area, and especially by the deep pits which mark the interambulacral 

 areas. These pits are comparable to those seen in Goniocidaris tubaria 

 (Lamarck) of the Australian region, but with the difference that they 

 are more deeply marked in C. foveata and do not run together in 

 grooves as they do in G. tubaria. This is still another case of a fossil 

 West Indian species finding its nearest living ally in eastern Pacific 

 waters. It is associated in the same lot, evidently from the same local- 

 ity with the Echinolampas ovumserpentis, Paraster sp. a, and Eupatagus 

 sp. a as here described. 



Eocene, from yellowish limestone, probably the Cambridge formation 

 of R. T. Hill, Jamaica, with no detailed locality; one specimen, holo- 

 type, Mus. Comp. Zool. No. 3234. 



Cidaris species a. (Text-figure 1.) 



The following is a description of this specimen : 



Primary spine long, slender, acicular, with 8 to 10 rows of low denticulate 

 ridges running parallel to the longer axis. The most perfect spine, which 

 is very nearly entire proximally, showing indications of 

 the milled ring and collar. It is incomplete distally. As 

 far as preserved, it measures 13 mm. in length and 2 mm. 

 in diameter at about the middle of its total length. 



This species is represented by one fairly complete 

 spine and a second fragmentary one on a slab of soft 

 yellow limestone. It differs from any other known 

 species of Cidaris occurring fossil in the West Indies, 

 but makes a very close approach in character to the 

 Recent West Indian species Dorocidaris rugosa H. L. 

 Clark (1907, Bull. Mus. Comp. Zool., vol. 51, No. 7, 



n*t\ t *. a *\ I - Cidaris sp. a. 



p. 210, plates 4, 5). Spine, x 3. 



Geologic age not known, probably Miocene, Ponce 

 Chalk, 2 km. southwest of Juana Diaz, from fallen 

 block of limestone alongside of the irrigation flume on flood-plain of 

 the Jacaguas River, Porto Rico, station 195, American Mus. Nat. 

 Hist. No. 18565, C. A. Reeds collector, Expedition of the New York 



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