100 DlCl'YOSPONGID^. 



extent, though it is highly probable that its resources are not yet exhausted. 

 Probably not less than two thousand specimens have already been collected 

 at this spot within a radius of five hundred feet from the district school-house 

 situated on the roadside. The species occurs here almost to the exclusion of 

 other organic remains. We have a record of three other sponges, Hydnoceras 

 rhopalwm, Jlijdriodictya patuln and Actinodictya placenta, represented by 

 single specimens, and also of a few crinoids and an occasional brachiopod. It 

 is especially important to observe that in this prolific development, variations 

 from the specific type, so far as the great amount of material studied would 

 indicate, are altogether rare, if not absent. The uniformity of specific charac- 

 ters is maintained throughout all the variations in size and development. In 

 the vicinity of this locality specimens have been found at various points within 

 a mile to the "west and south, and all of these occurrences appear to be at 

 about the same geological horizon ; they may prove to be offshoots or 

 extensions of the Brown hill colony. 



Elsewhere the species occurs in its normal proportions at somewhat 

 widely separated localities in the northern part of Steuben county and the 

 southern part of Ontario coiinty. A short distance north of the village of 

 Avoca, on the land of the late Thomas Co'itox, specimens occur in abun- 

 dance but in an inferior condition and showing a constant tendency to 

 assume the characters normal to the species H. Avoca ^ they have recently 

 been found in great numbers by Mr. D. D. Luther, about two miles southeast 

 of the village of Naples, Ontario county. The species has, iu fact, the most 

 general distribution in the Chemung rocks of any of the Dictyosponges, but 

 it does not range high in this series of faunas; although the specimen 

 described by Cojntbad was stated to have come, from Addison, Steuben county, 

 no examples of the species from so high an horizon have come under our 

 observation. 



The discovery of similar nodose sponges in the Psaramites du Condroz, of 

 France, the e(|uivalent of the Chemung sandstones of New York, has been 

 recorded by Bakuois.* The fossil which this author has referred to Dictyo- 

 pliyton titheroswm, Conrad, seems to represent a species clearly distinct from 

 any of the known American nodose forms, as is indicated by its deep hori- 

 zontal constrictions, sharp prismatic faces and low carinate nodes situated on 

 broad and stout horizontal annulations. This fossil is described and figured 

 elsewhere in this volume under the name, Hydnoceras Barraisi, and in 



* Sur les Dictyospongidee des Piiatnitiites du Condroz ; (Aunales de la Socictd Gdologiquo du Nord, 

 vol. xi, p. 80, pi. i, 1883), 



