144 NEW YORK STATE MUfcE:UM 



others are scattered over the surface of the slab. They suggest the 

 nonreticulate tuft or undifferentiated felt of spicules which is 

 common enough at the root of many living hexactinellids. The 

 position of these, however, is obviously not basal. Position, mode 

 of branching and some other features indicate that these sheaths or 

 tufts are terminal to the branches and represent compacted growth 

 ends. This consideration, not very easy to substantiate perhaps 

 among living sponges, is helped by the fact that the slab shows prac- 

 tically as many such sheaths as there are branches. Some are in 

 place and some apparently detached but there are many more than 

 the number of sponges would require as root-ends. 



In addition to these structures the slab shows some flat concentric 

 disks which would seem to be in all probability a part of these organ- 

 isms. These disks are depressed at the center and their concentri- 

 cally-lined surface is like that of the epithecal base of a Chaetetes 

 or Pleurodictyum. Such circular bases are not, however, foreign to 

 the living glass sponges and the association makes it probable that 

 these disks have served such a function here. 



In seeking comparison among the living Hexactinellids with this 

 singular branching Devonian sponge we find a suggestive species 

 in the Sclerothamnus clausi (Marshall) as depicted 

 in Schulze's Report on the Hexactinellida of the Challenger 

 Expedition (p. 33 7 ^ pi. 98). To institute more closely this com- 

 parison between two branching sponges the Challenger species is 

 here copied. Here the annular tufts appear to be not always 

 circular but at times continuous and spiral though the branching 

 is unlike that of the Devonian species, but so seldom does 

 branching occur that the two forms are comparable on that basis 

 alone. 



As we can no longer associate this species with the genus Cerato- 

 spongia it is now proposed to term this sponge Armstrongia, in 

 recognition of the intelligent interest taken in the collection of these 

 Devonian sponges, by Mr E. J. Armstrong of Erie, Pa., and the notable 

 additions to our knowledge of them which his specimens have con- 

 tributed. This slab, which was found loose, is from the upper beds 

 of the Chemung group, 9 miles south of Erie, Pa., and carries on its 

 back abundant specimens of a large Liorhynchus, probably L. 

 mesocostalis. 



