Memoirs of the Museum of Comparative Zool Ogy at Harvard College Volume 30

Memoirs of the Museum of Comparative Zool Ogy at Harvard College Volume 30

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 edition. Excerpt: ...Cup is compressed from side to side, and is thus wider in one horizontal axis than in the others. The folds increase in extent from the base toward the free edge. Below, the cup narrows to a base which is composed of two short irregular peduncular portions, situated close together. Total height of cup, 63 mm.; greater horizontal diameter, 110 mm.; smaller horizontal diameter, 55 mm. Thickness of lamellar wall in lower part of cup, 3 mm. Wall is thinner above, about 2 mm. thick just below the free edge. Edge itself is comparatively sharp. Both inner and outer surfaces of the cup are hispid with closely set styles, which project about 1 mm. beyond the surface. Consistency firm, but sponge easily broken. Color, light brown. The two surfaces are much alike, although one, the inner, is probably the oscular, and one, the outer, probably the pore surface. From both surfaces numerous main canals 300-500 fi in diameter and about 1 mm. apart pass radially into the body. They penetrate deeply into the body, the canals of opposite surfaces interdigitating as in Phakettia ventilabrum (Ridley and Dendy, 1887, Plate XLIX. Fig. 3). The canals debouching on the inner surface, efferent canals, open for the most part by single oscula nearly as wide as the canals themselves, and bounded by a narrow rim of oscular membrane. Rarely, instead of a single osculum there is a fenestrated membrane, including two or three apertures. Between the oscula the dermal membrane of this surface is perforated by scattered apertures of small size, 75-150 /a in diameter, resembling pores in appearance. Such small apertures are in some places abundant. The corresponding canals of the opposite surface, afferent canals, are roofed in by pore-membranes, which in some instances are...show more

Product details

  • Paperback | 122 pages
  • 189 x 246 x 7mm | 231g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236850432
  • 9781236850430