Hawaiian and Other Pacific Echini: The Salenidae, Arbaciadae, Aspidodiadematidae, and Diadematidae (Classic Reprint) - Softcover

Alexander Agassiz

Softcover

ISBN 10: 0243100434 ISBN 13: 9780243100439

Publisher: Forgotten Books, 2020

Synopsis

Excerpt from Hawaiian and Other Pacific Echini: The Salenidae, Arbaciadae, Aspidodiadematidae, and Diadematidae

The guadridenfate pedicellariae (pi. 45, fig. 1) are much less common than the tridentate, and are only known to occur in three species. They are usually found on the actinal part of the interambulacra. The head is shorter than the stalk, sometimes very much so, and there is practically no neck. The valves (pls. 45, fig. 2; 46, figs. 1, 2) range from about three fourths of a millimeter up to two millimeters in length and are straight and commonly more or less flat. They may afford useful specific characters. Doderlein found one of these pedicellariae with five valves, but we have never seen more than four.

The ovoid pedicellariae (p1. 45, fig. 4) are not very common, but are usually to be found on the interambulacra. The head (p1. 45, fig. 18) is about one fourth of a millimeter long, and is attached to the stalk by a neck of about the same length. The stalk itself is three to six times as long as the head. The three valves (pls. 45, figs. 5, 12, 23; 46, figs. 5, 6) are all alike and are dis tinctly longer than broad. They commonly lack an articular loop on the base, but this is occasionally present. For this reason, they seem to us to be modified ophicephalous pedicellariae, while D'oderlein considers them to be small tridentate. They are undoubtedly comparable to the triphyllous pedicellariae of other Echini, but are hardly sufficiently modified to be called by that name.

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About this edition

• Publisher: Forgotten Books
• Publication date: 2020
• ISBN 10: 0243100434
• ISBN 13: 9780243100439
• Binding: Paperback
• Number of pages: 160