﻿July, 1857.] 



ELLIOTT SOCIETY. 



235 



that these apparently idiosyncratic larvse represent the structure 

 of some other lower group of animals. But hitherto the larvse of 

 Echinoderms have excited the wonder of naturalists, by the fact, 

 that they appeared absolutely without representatives among per- 

 fect animals, either fossil or recent. Yet, in truth, according to 

 analogy, we must look hack to some distant geological period for 

 their representatives. Where, then, could we more naturally ex- 

 pect to find them than in the Palaeozoic Rocks, at a stage just 

 anterior to the epoch in which the first undoubted Echini proper 

 appear? And in this very position, the Graptolites, with their 

 remarkable resemblances to the skeletons of Echinoderm larvse, 

 present themselves like the disjointed letters, and words, and 

 phrases, of a fragmentary inscription, which, however, continued 

 labor may enable us to put together, and rightly to decipher. 



In short, so striking have these resemblances appeared to Mr. 

 McCrady, that before communicating his views, he would have 

 gone to work to reconstruct the animals, had he ever had a series 

 of Graptolites sufficient ; but there were so few good collections 

 of these fossils, that seeing no prospect of possessing a sufficient 

 suite of specimens himself, he had made the suggestion public at 

 once, in order that it might be tested by those who had the means 

 of doing so thoroughly. 



Another fruitful cause of difference between the appearances of 

 Graptolites and Echinoderm larvae, was, that the former had all 

 been pressed flat, into very thin laminse, in the course of their 

 fossilization. This made them appear, probably, broader than 

 they would have done otherwise, and might account, in many 

 cases, for the great number of teeth which appeared on the serrate 

 edge, by the suggestion that two edges were brought together by 

 the pressure, so as to appear as one, while their serratures were 

 in such a position, that a tooth on one edge should invariably 

 correspond to the interval between two teeth on the other. It, 

 also, would account for the more conical and suddenly tapering 

 form of the thorn-like process in the Graptolites, when compared 

 with its more cylindrical representative in the skeletons of Echino- 

 derm larvse ; for the inequality between the diameter of the base 

 of the process and that of its free extremity, would, of course, 

 be much magnified, if the structure were pressed flat. 



But Prof. Hall had fortunately found and figured (Pal. of New 

 York, vol. 1st, pi. 73, fT. 2n) specimens which had, at least, not 



