Twenty-two different echinoids are listed from the middle Tertiary rocks of Puerto Rico, although some of them are identified only to generic level. Echinoids are often numerous in these rocks and the assemblages are similar to those of other West Indian islands, but markedly different from the known faunas of comparable age from the surrounding mainland and of North, Central, and South America. The echinoid fauna of each Puerto Rican formation is discussed and one subspecies Clypeaster concavus puertoricanus, is describe as new.

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