374 Observations upon Stenqwra fibrosa, etc. 



concentric irregularities, the oblique lower terminations of the tubes, 

 arranged in a manner which resembled radiating lines. In a conical 

 specimen, IJ inches in height, and an inch in diameter at the upper 

 (broad) extremity, the increase in width had also resulted from a sim- 

 ilar mode of production ; but all the tubes necessarily ranged vertically, 

 and the conical surfoce exhibited also circular irregularities, as well as 

 terminations of the tubes, though less distinctly in that specimen than 

 in another of the same form. A mass of a nearly globular shape, 2h 

 inches in one diameter, and 3 in the other, had the surface almost Avholly 

 weathered, and therefore exhibited no clear characters ; but, internally, 

 the arrangement of the tubes agreed with that of the hemispherical 

 specimen. 



The original walls of the coral were apparently almost membranous, 

 and liable, under some conditions, to irregular contractions, as well as 

 considerable deviations in the line of growth; but in the large globular 

 mass such inequalities were far less conspicuous. 



The diaphragms, exposed in vertical sections, of all varieties of form, 

 were distributed over the whole surface, and without the least indica- 

 tion of grouping in bands. In the hemispherical and conical speci- 

 mens, which exhibited considerable irregularities in growth, the dispo- 

 sition of the diaphragms was very unequal ; while in the large globu- 

 lar mass, tiie plates, without observing any definite order, were 

 uniformly distributed. In some portions, however, of the other 

 varieties the number of plates corresponded; and the differences 

 displayed, may, it is believed, be rightly assigned to circumstances 

 which affected the mode of growth or production of the polypes, and 

 consequently modified the distribution of the diaphragms. 



With respect to the development of additional tuljes within the area 

 of those which pre-existed, it may be stated that divisional laminJB 

 were noticed in transparent, vertical slices of the hemispherical and 

 globose varieties, though less distinctly in the latter than the former ; 

 and that while in a similar section of the conical specimen they were 

 not satisfactorily detected, a transverse slice exhibited clearly divisional 

 lamina, rano-ing from opposite planes. The whole of these specimens, 

 moreover, proved clearly the powers which the polype mass possessed of 

 extending laterally and producing marginal tubes. 



Chetetes petropoliianm having been considered identical with Favosites 

 (Oietdes) fibrosa var. ghbosa of the Eifel, it is necessary to observe, that 

 in vertical sections of a specimen of the latter fossil, which belonged to 

 M. de Verneuil's cabinet, perpendicular divisional lamiuse within the 

 tubes were noticed, also fragments of the original coral, exhibiting only 

 interior surface walls, similar to those of Chetetes radians ; and it was 



