Anatomy of the Ventriculites of Mantel, 



339 



101 



fibre to another, by which the entire plexus is more firmly 

 connected together." 



The external coat, as it 

 appears on the best preserved 

 specimens in my collection, 

 may with propriety, I think, 

 be described as composed of 

 two laminae : the internal 

 spongious, and if there be any 

 particular course of its fibres, 

 it is from the base to the cir- 

 cumference, but the general 

 character is a confused dis- 

 tribution, indeed truly spon- 

 gious ; it is delineated at the 

 lower part of the specimen 

 Jig, 95. h : the external lamina 

 is a dense tissue, partaking 

 more of the nature of a coria- 

 ceous membrane or integu- 

 ment ; it is extended from the upper margin of the zoophyte 

 to the base, and continued over the radical processes ; it is so 

 beautifully delineated on the specimen in the plate given as a 

 frontispiece to vol. ii. of Parkinson's Organic Remains, that I 

 have not thought it necessary to increase the number of figures 

 in this place. 



I have with much attention compared Mr. MantePs figures 

 of the external surface with the specimens I have collected, 

 and I feel persuaded that what he has given as the external 

 surface are the concentric laminae, divested by fracture of some 

 of their exterior laminae at the point where the transverse tubes 

 terminate. In a state of great condensation by silicious infil- 

 tration, these concentric laminae are so agglutinated that they 

 lose all their delicate fibrous character ; the openings in them 

 for the passage of the transverse tubes vary also in form in 

 different specimens, being either circular, oval, or rhomboidal ; 

 and it is these circumstances combined that produce the ap- 

 pearance of an arrangement of large cylindrical fibres, and 

 which Mr. Mantel has been led to beheve constitute the exter- 

 nal covering. 



It appears, then, that this zoophyte is in the form of an in- 

 verted cone, and possesses a single cavity occupying its entire 

 body, in its contracted and elongated state resembhng the 

 finger of a glove, in its expanded state becoming a disk ; and 

 its base terminates in a pedicle that gives off radical processes 

 {Jg, 100.) by which it affixes itself to other bodies. Its struc- 



