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1. On the Structure of the Body-wall in the Spionidæ

Published online by Cambridge University Press:  15 September 2014

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Extract

In regard to external form, Nerine foliosa, Sars, is generally taken as the type of the family, and therefore it may be selected for structural examination in the first instance. Anteriorly the pointed snout is completed by the intricate interlacing of the muscular fibres beneath specially thickened cuticular and hypodermic layers. As soon as the body-wall assumes a rounded form, a layer of circular and oblique muscular fibres occurs beneath the hypoderm, the majority having the latter (i.e., the oblique) direction. In the centre of the area the oesophagus is suspended by strong muscular bundles (the most conspicuous of which are vertical) passing from the hypodermic basement-layer in the middle line superiorly to be attached to the œsophagal wall. A second series, as they descend to their insertion at the ventral surface, give lateral support to the tube; while a third group interlace in a complex manner, and, with the blood-vessels, fill up the space between the œsophagus and the wall of the body.

Type
Proceedings 1875-76
Copyright
Copyright © Royal Society of Edinburgh 1878

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References

page 125 note * The late M. Claparède, in his “Structure des Annél, Sédentaires,” p. 15, &c, pl. xv., gives the structure of the hypoderm, and notices the pennate muscles and the arrangement of the nerve-cords of this form, but the fore-going observations do not interfere with his remarks.