STE. GENEVIEVE MARLS NEAR FORT DODGE 605 



In the descriptions of the brachiopod species, which follow, 

 the main features only are described. Anyone desiring greater 

 detail and complete synonymy is referred to the excellent Mono- 

 graph on the Mississippian Brachiopoda recently prepared by 

 Doctor Stuart Weller. Page references to this monograph will 

 be cited under each species. 



We wish to thank Doctor R. S. Bassler of the United States 

 National Museum for kindly identifying the bryozoa. He finds 

 three species, two of them already described by Ulrich from the 

 Pella beds at Pella and the third is new. The material now at 

 hand is unfortunately toO' meager for section cutting. Further 

 collecting, it is hoped, will yield more of these interesting forms. 



The writers wish also to acknowledge the receipt of a small but 

 comprehensive collection from the marl made by Mr. Charles Ru- 

 benstein, a pupil of the Fort Dodge High School and an enthusi- 

 astic collector of local fossils. 



DESCRIPTION OF THE FOSSILS. 



SPONGES. 



CUonolithes lizardensis n. sp. 

 Plate XII, figs. 25, 26. 



Fine tubular burrows 0.1 to 0.25 mm. in diameter penetrating 

 the shells of brachiopods, especially those of Spirifer pellaensis 

 Weller. The burrows are circular to subcircular in cross section 

 and they ramify the shell structure in all directions. In parts of 

 some shells they are sufficiently numerous to cause partial disin- 

 tegration in much the same way that modem Cliona destroys the 

 shells of oysters and other bivalves. 



On the surface of the brachiopod shell they appear as minute 

 round holes subequally spaced and not especially crowded in any 

 of the specimens examined. In some shells the outer laminae of 

 the test have been so undermined that they have crumbled away ; 

 on the damaged surfaces the delicate sinuous tunnels and laby- 

 rinths may be readily seen. 



The generic term Clionolithes was proposed by Clarke^** for 

 this sort of remains in a very interesting paper on parasitic and 

 dependent forms of life. Doctor Clarke's specimens are from the 

 Devonian of the east. Similar material has been described by 



i«Clarke, J. M., 1908, "The Beginnings of Dependent Life," N. Y. State 

 Educ. Dept., 4th Ann. Rept. Dir. Sci. Div., Adv. sheets, pp. 25-28, plates 8-12. 



