480 Thirty-fifth Eeport on the State Museum. 



The frond consists of a continuous minutely reticulated tissue, 

 which is divided into longitudinal and transverse areas by bands of 

 acicular spicules. In a longitudinal direction there are twenty-four 

 bands, of two dimensions; the smaller ones corresponding in strength 

 with the transverse bands. The tissue occupying these twenty-four 

 rows of quadrules is alternately depressed and elevated, giving a low 

 nodose or bullate aspect to the surface. The tubercles show a radi- 

 ating arrangement of the spicules, and the superficial layer is often 

 extended from the summit into spiniform processes. 



The specimens obtained are fragmentary, of lengths varying from 

 50 to 80 mm., and widths from 40 to 70 mm. A single cylindrical, 

 flattened specimen has a length of 70 mm., and diameters of 40 and 

 30 mm. respectively. 



In the removal of these specimens from the matrix, the nodes are 

 frequently broken off, giving the appearance of a coarsely fenestrate 

 frond, and this condition has led to its identification with Uphan- 

 t^nta; but it is only in this broken state that it bears any resemblance 

 to that genus. The surface, when entirely preserved, consists of a 

 continuous reticulate tissue,a character never existing in TIphant^enia. 



Formation and locality. In the shales of the Keokuk group ; 

 Crawfordsville, Indiana. 



Physospongia Colletti, n. sp. 



Plate 20, Fig. 7. 



Frond cyathiform, more or less rapidly expanding above. Entire 

 form unknown. Base unknown, but probably abruptly attenuate. 



Substance composed of a very finely reticulate continuous tissue. 



Surface divided into eight distinct areas by strong radiating ridges 

 composed of bundles of spicules. These areas are longitudinally di- 

 vided, each into two smaller fields, by a finer longitudinal band. The 

 entire surface is traversed by transverse bands which, with the radi- 

 ating bands, divide it into small quadrules, which are alternately ele- 

 vated and depressed, giving the surface a bullate appearance. These 

 quadrules are wider than high. The principal radiating bands are 

 strong and regular. The transverse bands are regular and of uniform 

 size; and the intermediate smaller radiating bands are irregular, 

 sometimes giving rise to three or four bullae and corresponding de- 

 pressions between the main radii, while the normal number seems to 

 be two. 



The dimensions of the principal specimen described are as follows : 

 Vertical height, 85 mm.; transverse diameter at the lower margin of 

 'the specimen, which is compressed, 85 mm.; the transverse diameter 

 at the upper margin is 150 mm. Fragments of much larger individu- 

 als have been observed. 



Formation and locality. In the shales of the Keokuk group ; 

 Crawfordsville, Ind. 



