Spkcies of the Keokuk Group. 167 



DiCTTOSPONQIA (?) STTLmA, Sp. nOV. 

 Platk lvi, Fia. 2. 



Among the material from Crawfordsville is a slender elongate fossil 

 whose sponge nature is strongly suggested by a comparison with the graceful 

 Chemung species, Dictyospongia lophura. It is therefore noticed here, 

 although its precise relations may still be somewhat obscure. 



The fossil is narrow and subcylindrical, expanding from the basal point 

 to the full diameter of the cup in about one-eighth the length of the specimen. 

 The surface is smooth and covered with fine, closely" set vertical lines. The 

 evidence of transverse lines is not very satisfactory; there is, however, a 

 series of comparatively broad and low transverse depressions which are 

 plainly developed over the upper part of the specimen, and these contract 

 toward the upper extremity, producing, with the vertical lines, the effect of 

 an elongate rectangular reticulation. Below this extremity the transverse 

 depressions produce a somewhat undulating surface. 



The specimen has a length of 91 mm. and a diameter of about 6 mm. for 

 seven-eighths of its length. There is no evidence of a spicular tuft at the 

 basal extremity. 



Locality. In the calcareous shales at Crawfordsville, Indiana. 



DiCTTOSPONGIA (MaSTODICTYa) 080ULATA, Sp. nOV, 

 PuLTK LTi, Fig. 6. 



The figure cited represents one aspect of a sponge of whose complete 

 form it is not possible to obtain an accurate conception from the material in 

 hand. If the peculiar shape presented by it is normal or essentially so, as it 

 seems to be, then this species represents a distinct type of generic structure 

 which, if established by future investigations, may be known as Mastodiotya ; 

 but it is still possible that the shape of the sponge is more or less due to com- 

 pression or other casual cause. Hence the characters of the fossil are here 

 described from the single example known, while its generic and specific values 

 are left contingent upon the discovery of additional material. 



The lower, broken extremity of the specimen has a width of 20 mm. and 

 thence it gradually widens upward into the bulbous swellings. Here the 

 diameter of the cup has increased to 24 mm. The swelling at the right con- 

 tracts quite abruptly and apparently terminates in an osculum or excurrent 

 orifice at 7 mm. above its gi-eatest diameter ; the portion on the left however 

 is much more produced, contracts more gradually, extends to a distance of 

 23 mm. above the swelling and at the ai^erture has a diameter of 4 mm. 



