Spkcikh ok thk Ciikmun*-, Gkoijp. 143 



there is a very, similar irregularity in the sponge meshes produced by the 

 intersection of spicular bands at varif)us angles, while the rectangular inter- 

 section is to some degree retained.' Though Walteria is a cup-shaped 

 sponge, the structure of its reticulum indicates that these fossil bodies, 

 AcTiNODicTYA, are correctly construed as hexactinellid sponges. 

 Type, Actinodictya placenta, Hall. 



AoTrNODICTYA PLACErTTA, Hall. 

 Plate xxx, Figs. 1-3; Platb xxxi, Figs. 1, 2. 



1890. Actinodictya placenta, Hall. Ninth Ann. Rept, N. Y. State Geologist, 

 p. 60 ; Forty-third Ann. Rept. N. Y. State Museum, p. 262. 



Sponge explanate, broadly depressed-convex, most of the specimens 

 having a suboval though unfinished outline, occasionally with margins deflected 

 or incui-ved. Surface without nodes but covered with spicular ridges of 

 various sizes, the larger usually crossing the frond through its entire length, 

 the smaller being traceable for a less distance; these ridges crossing one 

 another in all directions without obscuring a certain degree of rectangular 

 reticulation. The margins of the specimens are not defined by any of the 

 spicular bands. The variation in size from the coarsest to the finest bands 

 is very considerable. The surface of these fronds is usually of a darker color 

 than the matrix, and this fact contributes to the actual appearance of the 

 specimen in evincing the very close interweaving of the spicular bands. 



Localities. This species has proven to be quite abundant in some of the 

 lower or middle strata of the Chemung group in the vicinity of, and to some 

 extent in association with the colony of Hydnoceras tuberosum at the Brown 

 hill school house near Wallace, Steuben county. A few specimens have come 

 from this spot itself, and about a half-mile away, upon the farm of Mr. John 

 Roth, a considerable number of fine specimens has been collected by Mr. Jacob 

 Van Deloo, in close proximity to the horizon of H. tuberosum. A few miles 

 to the southeast, in the town of Howard, Mr. D. D. Luther has found some 

 loose arenaceous slabs undoubtedly derived from the immediate neighbor- 

 hood, and which are nearly composed of small fronds of this sponge. 

 Among the earliest specimens of the species found are some from the upper 

 Chemung beds near Lawrenceville, Tioga county, Pennsylvania, collected in 

 1879, by A. S. Sherwood. Associated with it in the localities in Steuben 

 county are Atrypa hystrix, Spirifer niesacostalis, Productella lachrymosa, and 

 Poteriocrinvs Glarhei. 



