Hawaiian And Other Pacific Echini The Salenidae Arbaciadae Aspidodiadematidae And Diadematidae

Author : Alexander Agassiz
Publisher : Forgotten Books
ISBN 13 : 9780266511526
Total Pages : 160 pages
Book Rating : 4.5/5 (115 download)

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Download or read book Hawaiian and Other Pacific Echini written by Alexander Agassiz and published by Forgotten Books. This book was released on 2017-10-19 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.