308 Verrill, JVotes on liadiata. 



lection there are two specimens,* received from the Boston Soc. Nat. 

 Hist., and collected by different persons, labeled " Gulf of Mexico?" 

 which I have considered the HeliocidaHs Mexicana Agassiz. But 

 these belong to the genus Anthocidarls of Ltitken. Should this 

 identification prove correct, the name, Anthocidaris mexicana, ii^ay 

 be applied to this species, while the species from Acapulco, since it 

 apparently belongs to a distinct genus, might be allowed to retain the 

 same specific name, but until described this name can only be consid- 

 ered as provisional, and not entitled to priority. For these reasons 

 I leave this species without a name, for the present. 



Echinometra rupicola A. Agassiz, BuUetiu M. C. Z., p. 21, 1863. 



Mr. Bradley sent numerous examples of this species from Panama 

 and the Pearl Islands, where it occurs on the reefs at low-water mark, 

 and in rocky pools. It has the habit of forming excavations in the 

 rocks in the same manner as Euryechinus lividus of Europe, most of 

 the larger specimens occurring in such cavities. He also obtained 

 specimens at La Union, San Salvador, and Zorritos, Peru. From the 

 latter locality the specimens are very large and beautiful. 



Our largest specimen measures, in the greater diameter of its test, 

 3-2 inches ; smaller diameter 2-8 ; height 1 '5 ; diameter of actinal open- 

 ing 1-1 ; of abactinal area, including genital plates, '45. The spines are 

 variable in length ; usually the longest, in large specimens, are from 

 1 to 1'5 inches long. In a specimen having the test 1*5 inches in di- 

 ameter some of the s})ines are 1*6 long. 



The test is broad oval, or subcircular, depressed above, regularly 

 arched on the sides, rather flat beneath. Actinal cuts deep and nar- 

 row. Interambulacral zones are a third wider than the ambulacral, 

 with at least six rows of large tubercles, those in the next to the 

 outer one largest, continuing to the genital plates. Ambulacra with 

 four rows of smaller tubercles, those of the two median rows largest 

 and regularly arranged, about equal in size to those in the outer row 

 of the interambulacra. In the largest specimen there are 24 ambula- 

 cral, and 18 interambulacral tubercles in the principal rows. Porifer- 

 ous zones rather wide, with seven or eight pairs of pores in well 

 curved arcs. The u})per pair in each arc is between the outer and 

 median rows of ambulacral tubercles. Genital plates of moderate 

 size, outward edge acutely angular, openings large ; ocular plates 

 reaching the anal area. Spines slender for this genus, regularly taper- 

 ing to the acute ends, more ecpial in size than usual, the second series 

 being less numerous. Color dark purple throughout. 



* Mr. A. Agassiz considers these, Echinometra plana A. Ag., — Reprint. 



