Pkkfack. 5 



Broome counties have yet to be as carefully explored for these fossiln an 

 have been Allegany, Cattaraugus and Steuben counties. 



To thelatelleverend Jonathan Allkn, former president of Alfred Univer- 

 sity at Alfred, Allegany county, an early and interested collector of these 

 sponges, I owe many favors. From him, by loan and purchase, I obtained some 

 interesting specimens, and at one time employed his son to make collections 

 from the localities in and about Alfred. 



Mr. T). Dana Litthku, both before and during his engagement tipon the 

 geologic work of this depai'tment, has supplied a number of intei-esting 

 forms from the lower beds of the Chemung group in Ontario, Yates and Steuben 

 counties, and has I'ecently discovered DicTYospoNoiiKii; in some variety in the 

 shales and sandst(mes of the Portage group, in Wyoming and Ontario counties; 

 a formation from which they had not been previously obtained. 



As early as 1883, Professor Ciiakles Barkois, of the University of Lille, 

 demonstrated the existence of Dictyospongid^ in the Psammites du Condroz of 

 Brittany. The forms which were described by hina are noteworthy in their simi- 

 larity to those occurring in our equivalent geologic horizon, the Chemung group. 

 Professor Barrois, Avith most courteous liberality, has placed these specimens, 

 together with some later collections from the same horizon, in my hands for 

 comparative study, with full permission to illustrate and describe them. As 

 no other part of the world has yet furnished species so closely allied to the 

 American Dictyosponges, we have gladly availed ourselves of this privilege and 

 these French species will be foxmd fully described and illustrated in this 

 volume. 



Further, — to the following gentlemen and institutions, acknowledgment 

 is here made for their courtesy in the loan of specimens. 



Sir AViLLiAM Dawson, of Montreal, whose important descriptions of 

 various beautiful forms of Protospongid^ from the slates at Little Metis are 

 well known, and who has kindly loaned a nearly complete series of his species 

 for comparative study. 



Mr. A. S. Tiffany, of Davenport, Iowa, for the loan of specimens from 

 Crawfordsville, Indiana, representing the new genus Lkbedictya, and specimens 

 of Clatiirospongia both from the locality mentioned and from the Waverly 

 group of Ohio. ,, 



Mr. J. F. Carll, of Pleasantville, Pennsylvania, who has supplied speci- 

 mens from the lower Carboniferous rocks of Pennsylvania, upon which we 

 have established the species Cidathospongia Carlli. 



