834? Anatomy of the Ventriculites of Mantel. 



gious, gelatinous ; external surface reticulated ; internal sur- 

 face covered with openings or perforated papillae; base 

 imperforate, prolonged into a stirps, and attached to other 

 bodies." 



The following observations, offered as contributions to the 

 anatomy of this zoophyte, are the results of repeated examin- 

 ations of an extensive series of specimens, chiefly impreg- 

 nated with, and enveloped in, flint. They are in various states 

 of preservation ; and, although from the fragile nature of the 

 matrix their structure has been much deranged by fracture, 

 still I find the silicified remains exhibit the original structure 

 more distinctly than the calcareous ; and from the former 

 (except in one instance,^. 100.) I have taken the accompany- 

 ing sketches. 



These bodies are commonly found enveloped in flint, 

 forming the nucleus of nodules of that substance, and as- 

 suming various forms, usually pyriform, but occasionally that 

 of the mushroom ; in the former case, they are readily dis- 

 tinguished by a spongoid circle bordering the smaller ex- 

 tremity, which is the margin of the mouth of the contracted 

 original, and numerous perforations around the opposite 

 extremity, exposing the terminations of the diverging radical 

 processes ; in the latter case, the spongoid structure appears 

 on the margin of the summit, and the perforations at the 

 bottom of its stalk. Mr. Mantel has given some faithful re- 

 presentations of these flints in tab. 10. of the work above 

 referred to ; and he has observed, that, " the margin is marked 

 with semilunar indentations, the impressions of the fibres of 

 the external integument; .... these markings are pecu- 

 liar to the fossils of this genus, and attention to this circum- 

 stance will frequently enable the collector to distinguish the 

 silicious specimens of Ventriculites from those of ASpongus 

 Townsend?." 



From my dissections (if I may so term my investigations), I 

 am led to describe the original zoophyte as constructed of 

 various coats or layers, which may be separated into an 

 internal, an external, and a series of concentric lamince, 

 through which pass transversely, and afterwards longitu- 

 dinally, a number of tubes destined to contain the materials 

 for the support and growth of the body. I proceed to de- 

 scribe these parts separately as they have appeared to me. 



Inner Coat, — This appears of a spongious texture, and 

 lines throughout the ventricular cavity. It is probable that 

 this coat is nothing more than the inner layer of the reticu- 

 lated substance forming the chief mass of the animal, having 

 gelatinous fibres irregularly interwoven, and forming a com- 

 plete spongiqus texture. In the contracted and elongated 



