llie Life-Hisfory of Spirifer Iwris. 145 



These ure the data preserved for us in the rocks, from which 

 we are to determine the sjjecific character of the shelh Tliese 

 are all morphological characters, and the species they define is 

 plainly a morphological species ; and it is by study of these 

 facts that the history and the relations of the species, and its 

 true limits and nature, can alone be determined. A comparison 

 of this with other forms reveals some very interesting facts. 



Firat. — The second specific characteristic {b), namely, the size, 

 is known to vary easily and rapidly under changed conditions 

 of food and climate, and other environ-conditions. In a com- 

 parison of forms of diifereut geographical or geological areas, 

 the difference in size may be safely regarded as of varietal im- 

 portance, but taken alone is scarcely of specific importance, 

 using S23ecics in the strictly morphological sense. 



In the present case, in the layer in which the species first ap- 

 pears, the individuals are very abundant, — and actually massed 

 together, — the majority of them being as large as the average, 

 some larger than any yet observed above the bottom layer ; but 

 also with these are many small individuals, less than half the 

 size of ordinary specimens, and others still smaller, running- 

 down to minute ones, scarcely the size of a pin-head. In 

 these smaller individuals, are seen characters relating them to 

 varieties of Spirifer fimbiHatus, Conrad, of the Hamilton beds 

 below ; but thej^ are plainly young or immature forms of the 

 tS. Jmvis series, being found from the smallest through the 

 intermediate to the normal adult *S'. Icevis. 



A young specimen of S. fimiriafus, C, from the Tully lime- 

 stone of the upper Hamilton, is seen in the University collection, 

 which could not be certainly distinguished, specifically, from 

 the young of S. Icevis of the Portage, if the two occurred in the 

 same bed. 



I am inclined to consider the forms called Ortliis suiumbona, 

 in the 10th Regents' Report, and identified as Amboccelia in the 

 13th Report, and as Spirifer in Hall's final Report on the 

 Brachiopods (Pal. of N. Y., vol. 4, p. 234), as only an extreme 

 variety of the typical form, called Spirifer fimbriatus, Con. 

 It ranges throughout the Hamilton, but, as specific names are 

 now applied may as well kce}) the specific name. 



