340 Anatomy of the Ventriculites of Mantel, 



ture is, an inner coat, from which arise with open mouths the 

 transverse tubes that enter a reticulated parenchyma in concen- 

 tric layers {the concentric lamince) constituting the chief sub- 

 stance of the animal, and this parenchyma is enveloped in an 

 external coat, the exterior of which possesses the character of 

 a coriaceous and elastic integument. 



Of the economy of these various parts, we may fairly con- 

 clude that the cavity is ventricular, for the reception of the 

 animars food, and in which it is digested : the tubes are a sort 

 of receptdcula chyli, in which the nutrient particles, absorbed 

 by their open mouths, are assimilated and conveyed to all 

 parts of the animal, and afterwards deposited in the substance 

 for its support and growth, by the tubuli radiating from the 

 larger vessels : the concentric lamince are the portion of the 

 animal which possesses the function of contraction and expan- 

 sion ; I am led to conclude these properties reside in this tex- 

 ture rather than in the external integument, from the monili- 

 form state of the reticular fibres of these laminae when under 

 contraction ; an appearance never observed (that I am aware 

 of) in the texture of the external coat, and, therefore, the ex- 

 ternal integument I consider as little more than a defence to the 

 softer parts beneath it. The pedicles are similarly constructed 

 to the body, except that the ventricular cavity is not extended 

 into them, and consequently the inner coat makes no part of 

 their structure. 



In our specimens the different parts are found in various 

 states of preservation,, and exhibit varying features according 

 with the portion of structure that may be exposed to view. 

 The pyriform and fungiform nodules of flint before mentioned, 

 upon fracture with a well-directed blow of the hammer, some- 

 times afford you a complete cast of the ventricular cavity, ex- 

 hibiting the arrangement of the open mouths of the absorbent 

 vessels ; but, in many instances, the organic body is so infil- 

 trated with silicious matter, that all traces of organisation are 

 obliterated, and you can only distinguish the outline of the 

 substance, and its ventricular cavity, by the different shades 

 of colour of the mineralised body and its matrix ; the former 

 sometimes having a reddish brown colour, at other times a grey 

 or lighter shade than the usual black of the latter. In some 

 cases, the organised body is less impregnated with silex, and 

 being usually hydrophanous, the spongious texture is beauti- 

 fully displayed on wetting the specimen with water. 



It remains for me now but to enquire in what portion of the 

 scale of animated nature, we are to place this organic remain. 

 Mr. Mantel was " led to conclude that the Ventriculites were 



