SOME NEW PALEOZOIC GLASS-SPONGES FROM 
IOWA 
A. O. THOMAS 
Fossil sponges of any kind are relatively rare in the Paleozoic 
rocks ,of Iowa and especially so if we except the questionable 
forms generally relegated to the Receptaculitidae. 
Briefly stated the record stands about as follows: in the Ma- 
quoketa beds are a few zones in which Hindia parva Ulrich is 
fairly common ; in the dolomitic Hopkinton beds of the Silurian are 
rare examples of Astylospongia christiani M. and W. ; in certain 
Devonian horizons are examples of the thick-walled, convexo- 
concave Astraeospongia hamiltonensis M. and W. ; in the same 
system the shells of occasional brachiopods and molluscs show 
considerable evidence of the ravages of a tiny boring sponge be- 
longing to the genus Clionolithes and there is record of similar 
depredations on Mississippian brachiopods; the Burlington lime- 
stone has furnished one Dictyosponge, Lyrodictya burlingtonensis 
Hall and a specimen of Belemnospongia fascicularis Ulrich; and 
lastly Ulrich has described a species of Lasiocladia from the 
Keokuk limestone. 
Recurring to the Receptaculitidae, the large discs of Recep- 
taculites oweni Hall, the so-called “sunflower coral” of the lead 
and zinc miners, are abundant in at least two zones of the Galena 
dolomite in the vicinity of Dubuque and at other localities where 
this part of the Ordovician is exposed. Of less common occur- 
rence but associated with R. oweni and belonging to the group 
are specimens of Ischadites iowensis (Owen). Fragments of a 
Receptaculites, close to R. occidentalis Salter, are found in the 
Silurian. Another Silurian receptaculoid form is Cerionites 
dactylioides (Owen) ; in places the rock is crowded with repre- 
sentatives of this species and whatever their habits or lineage may 
have been they lived in dense groups whose numbers suggest 
prolific sponge colonies similar to those of the Tennessee Silurian. 
The remarkable glass-sponge colonies of the Upper Devonian 
of New York and Pennsylvania are without their equivalents 
numerically anywhere in North America as far as known. In- 
deed these remote ancestors of the beautiful Venus’ Flower Bas- 
ket of our modern seas are but meagerly represented paleontologi- 
