Echinoidea by Theodor MortensenEchinoidea by Theodor Mortensen


byTheodor Mortensen

Paperback | January 14, 2012

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This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1904. Not illustrated. Excerpt: ... distinctly crenulate, and there may be indications of a stellate structure at their base. The secondary tubercles are rather numerous, in larger specimens very crowded, forming more or less distinct vertical and horizontal' series; especially inside the primary series there is a vertical series of secondary tubercles, which may be almost as large as the primary ones; they may be more distinct in the ambulacra than in the interambulacra. The pores are very small,' disposed in a very nearly straight series, close to the edge of the area (only at the ambitus a little distant from the edge in the largest specimen), no tubercles being found outside the pores. The poriferous zone is very narrow, only ca. '/?--Vs as broad as the interporiferous zone. The ambulacral plates are as high as the interambulacral ones, their number being the same. The small pits at the outer edge of the area are very indistinct or quite wanting. Apical system (PI. II. Fig. 6). The genital plates show the peculiar feature of the outer part with the genital opening being separated from the inner part by a distinct, mostly curved line, so that it seems as if the plate were divided in two parts, which is, however, not really the case. Sometimes the transverse line is obscured by tubercles, but never, so far as my experience goes, on all the plates; on the madreporite it is never distinct. The outer part of the genital plates is mostly darker coloured than the inner part. There is a circle of tubercles along the inner edge. The genital opening is placed near the outer edge. The ocular pore is placed on the outer edge of the rather thick ocular plate and cannot be seen from above; the part of the plate outside the pore is white and looks like a small distinct plate. The depression between ocular an...
Title:EchinoideaFormat:PaperbackDimensions:66 pages, 9.69 × 7.44 × 0.14 inPublished:January 14, 2012Publisher:General Books LLCLanguage:English

The following ISBNs are associated with this title:

ISBN - 10:0217582702

ISBN - 13:9780217582704

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