184 The Ohio Journal of Science [Vol. XX, No. 6, 



Campeloma, Amnicolidce and Valvata and the presence of 

 Segmentina and Pomatiopsis. The occurrence of Goniobasis is 

 difficult to account for; possibly it is a case of adaptation. 



There is hardly a doubt that the Castalia marl is of com- 

 paratively recent origin, possibly still in the process of formation 

 in the eastern marshy part of the area. It would be worth 

 while to study more exactly than has been done, the present 

 fauna of the vicinity and compare it with that of the marl. 



CONCLUSION. 



The two lists, though probably not complete, show that the 

 faunas under consideration are radically different. The Tinkers 

 Creek deposit is a lake or pond formation. As has been pointed 

 out, the few land snails may be left out of consideration, since 

 the fauna is essentially lacustrine, even with a few amphibious 

 species missing. The Castalia fauna, on the other hand, is for 

 the most part terrestrial, there being fifty species of Stylom- 

 matophora and Carychium. By a coincidence the numbers of 

 Basommatophora in each list is about the same, twenty-one, 

 nine of which are common to both : 



Lymnaea humilis modicella and rustica. 



Planorbis trivolvis, the common form abundant at Castalia 



with nothing like binneyi, which (alone) is scarce at Tinkers 



Creek. 

 Planorbis parvus, the only species abundant at both places, but 



represented by markedly different forms; 

 Planorbis crista, scarce in both ; 

 Ancylus Kirklandi, and pumilus, apparently in both; 



Gundlachia -, one specimen in each; 



Physa gyrina, and Integra, somewhat different forms. 



Of Streptoneura, Tasnioglossa, there are eight in all, six at 

 Tinkers Creek, two at Castalia, none of them common to both. 



Sphaeriidae: about nineteen species, all at Tinkers Creek, some 

 common to abundant, others apparently scarce; six of 

 Pisidium are also at Castalia, all scarce. 



There is a total of 110 species, only 15 of which are common 

 to both faunas. 



New Philadelphia, Ohio. 



