1848.] LONSDALE ON FOSSIL ZOOPHYTES. 101 



composed of salient and re-entering angles, proving considerable 

 lateral interference ; yet it was difficult to determine how far the 

 severed portions gave freely parted walls. The apparently outer 

 sides of these compressed hollows were punctured in the manner 

 mentioned in noticing the composition of the tubes ; but if rightly 

 understood, the best exhibited surfaces were not smooth, although 

 they displayed no rough broken edges or points indicative of a frac- 

 tured intermediate structure. The nearly perfect exteriors, it must 

 be remembered, afforded very faint or no signs of a dividing line ; 

 and the supposed thickened area had a continuous layer around and 

 between, intimating a complete union in that state. These imper- 

 fectly observed characters are nevertheless believed to be in nowise op- 

 posed to the conclusion of the adjacent walls having been unconnected 

 when first developed. The foramina in their sides were necessarily 

 designed for a specific purpose ; and possibly they afforded a passage 

 to vessels that nourished the animal substance which occupied the 

 narrowest as well as the broadest interspaces ; and as this portion of 

 the polype was unprovided with the means for forming a definite 

 structure, calcareous matter was probably deposited in a pulverulent 

 state, filling partially or wholly the finer intervals, and clouding 

 more or less the wider, according to the relative age or position of 

 the examined fragment. Whatever may have been the real nature 

 of these spaces, or the functions of the animal matter, it is perfectly 

 clear the polype-tissues which constructed the whole body of the 

 coral must have had a far simpler organization than those that de- 

 veloped the solid fabric of SipJiodictyum gracile. Better examples 

 of the impropriety of limiting the term polypus to the viscera and 

 the appendages around the mouth could not be advanced. In both 

 the fossil genera, the digestive apparatus and the tentacula could not, 

 reasoning from what is known of existing ascidian zoophytes, have 

 differed greatly ; whereas the animal matter which occupied the in- 

 terspaces, and in one case produced a complicated structure, but in 

 the other has left scarcely a trace of a regular composition, could 

 have possessed little organic sameness. Limit the term polypus to 

 the portions that filled the tubes, and the animals might be consi- 

 dered identical ; extend it to the whole of the soft parts, and the 

 most marked differences become apparent. 



Additional ca^-ities sprang chiefly from the direct centre, but a 

 minute circle or angular area could be detected occasionally nearer 

 the circumference, and in some cases they were arranged on each 

 side of a faint curved line which traversed more or less medially 

 cross sections. Though no direct evidence was obtained, yet these 

 lines were considered as precursors of a bifurcation. They were 

 clearly not the effects of anastomosis. 



The foregoing statements, it is conceived, justify the inference that 

 the extinct coral was formed by an ascidian polj^e ; and that it 

 should be placed provisionally among the Tubuliporidee. 



