PALEOZOIC GLASS-SPONGES 
87 
a fine mesh of small oblong quadrules whose longer dimension is 
up and down the surface and the pattern is without variation 
over the exposed part of the specimen. Transversely the quad- 
rules average about twenty-two to the centimeter while vertically 
the number is between eight and nine to the centimeter, hence the 
length of each quadrule is about two and one-half times its 
breadth. The transverse lines are more wavy than the vertical 
ones. On the expanding lower part new lines come in between 
the others at irregular intervals. There is no evidence of a 
basal tuft. 
Length of specimen 125 mm., width at the midlength 34 mm., 
greatest thickness of the part above the matrix 14 mm. 
Position and Locality: Middle Silurian or Niagaran beds, 
near Hopkinton, Iowa. Collected by Samuel Calvin. It is mu- 
seum number 2800. 
IOWASPONGIA n. g. 
Large vase-shaped or fusiform sponge. Surface marked by 
prominent, sharp-edged, horizontal annulations separated by broad- 
ly concave interannular spaces. It has no nodes or protuberances. 
Aperture and tip unknown. 
It is of the general type of Ceratodictya of Hall and Clarke. 
IOWASPONGIA ANNULATA n. s. 
Plate I, Figs. 2, 3, 5 
Descriptions based on three incomplete specimens whose in- 
teriors are filled with the plastic shale of the matrix. 
Body large, vase-, or spindle-shaped, approximately circular in 
cross-section. Upward expansion rapid in the lower part, then 
gradual, with evidence of becoming narrower above. Body 
marked by sharp and prominently elevated annulations which are 
farthest apart about the middle and become progressively closer 
together both apically and basally. 
Specimen a is 130 mm. long, 158 mm. in greatest diameter, and 
91 mm. in diameter at the lower end. It has eight annulations, 
the circumferences of which as well as the width of the inter- 
annular spaces gradually increase upward for the first five rings, 
while the remaining rings and spaces have nearly equal circum- 
ferences and widths respectively. When complete the indvidual 
was close to a foot in length. 
Preservation is such that only a carbonaceous stain or film is 
