CONTRIBUTIONS TO THE PALEONTOLOGY OF NEW 



YORK 



DEVONIAN GLASS SPONGES 



BY JOHN M. CLARKE 



I The Ontogeny of Hydnoceras 



(Plate I) 



The interesting specimen here illustrated was recently sent to the 

 State Museum by Mr L. D. Shoemaker of Elmira. It is a slab 

 of sandy flagstone found near the village of Wellsburg, N. Y., 

 6 miles southeast of Elmira. One surface of this slab carries, as 

 represented, two essentially entire and mature individuals of 

 Hydnoceras, undoubtedly of an undescribed species, which lie side 

 by side as they must have stood when they were growing erect on 

 the sea bottom. The specimen is otherwise rather full of fossils 

 characteristic of the Chemung fauna, principal among which is the 

 little brachiopod Ambocoelia gregaria. 



The genus Hydnoceras has been abundantly described and it 

 would seem as though almost every variety of expression is mani- 

 fested in the various species represented in the Monograph on the 

 Fossil Reticulate Sponges.^ In the preparation of that somewhat 

 exhaustive treatise, very abundant material was available, and in 

 the study of the representatives of this nodose and highly specialized 

 genus Hydnoceras, it was desirable, at times to emphasize local 

 variations in form and character of surface which might not have 

 been so distinguished had the specimens been found in the same 

 place or colony. In other words, it became very evident in the 

 study of the various local colonies of this genus of sponges, in 

 some of which the individuals grew by hundreds and thousands, 

 that there was in many cases a distinct local impress which prob- 

 ably, on careful weighing of the evidence, would be found not to 

 equal species values. 



We there also indicated that morphologically, the simplest type of 

 expression in these sponges is the obconical, sm,ooth tube or 

 reticulum; that is a skeleton without any division into nodes, rings, 

 tufts or other surface modifications. This type is maintained in the 

 greatest abundance throughout the climacteric development of these 



'Hall, James & Clarke, J. M., 1898. 



[177] 



