Eeport of the State Geologist. 19 



logic formations in which they occur. The genera described 

 number 156 and the species enumerated are about 1,100. The 

 main portion of this second part is devoted to diagnoses of the 

 genera, illustrated by about 200 figures in the text and by 25 

 plates. 



This paper was originally o.ommenced by the writer, at the 

 request of the Secretary of the Board of Eegents, to fill the 

 place of Bulletin No. 1 of the St-ite Museum publications by the 

 Eegents of the University. The plan of the work, at that 

 time proposed, was mainly a description and illustration of 

 the Palaeozoic genera of Bryozoa which had been illustrated in 

 volume 6 of the Palaeontology of I^ew York. This work was 

 carried on at my personal cost nearly to completion; 22 of the pro- 

 posed 24 plates having been prepared for the lithographer, with the 

 manuscript essentially complete, but when offered to the Secre- 

 tary for publication it was declined, and the matter left on my 

 hands. The work has since been turned over to Mr. Simpson to 

 be completed m his own way, while the generic descriptions and 

 the explanation of plates of the original paper still remain in the 

 writer's possession. 



In completing this memoir Mr. Simpson has elaborated the 

 work, adding thereto the discussions upon the recent Bryozoa^ 

 with full illustrations, and the entire work in its present form is 

 communicated as a part of the report of the State Geologist. 



The Palaeozoic Reticulate Sponges of the Family 

 Dictyospongidae. 



A Family of Palaeozoic Hexactinellid Sponges, with Descrip- 

 tions of the Genera and Species. 



This work is a monograph of a single family of thin-walled 

 reticulate silicious sponges whose life was restricted to Palaeozoic 

 time. These fossils were early described as remains of marine 

 algae and a few species from the latter Devonian rocks became 

 pretty well known to the collectors of New York State fossils- 

 Their true sponge nature was recognized about fourteen years ago 

 by Prof. R. P. Whitfield, from the study of specimens found in 

 the soft calcareous shales of Crawfordsville, Indiana, which 

 retained the pyritized spicular skeleton of the sponge. 



