buffalo society of natural sciences 253 



Summary of Facts of Distribution on Continent of At- 

 lantica. We are now enabled to bring togtther all of the many 

 lines which we have been following in tracing the affinities of the 

 faunas which for other reasons were supposed to have come from the 

 continent of Atlantica, and here, as in the case of the faunas of 

 Appalachia, the great weight of evidence shows that the Bertie, 

 Rondout, Manlius, Ludlow, Lanarkian, Baltic, and Old Red faunas 

 are more closely related inter se than they are to the faunas which 

 from the study of the petrogenesis of the formations in which they 

 occur, were believed to have come from other continents. 



The Eurypterld Faunas of Mississippia. So far only a single 

 fauna is known from the continent of Mississippia, and therefore it 

 is not possible to institute any comparisons between the species found 

 in that fauna and those from other faunas on the same continent, 

 as was possible in the case of Atlantica and Appalachia; the most 



Fig. 28. Eurypterus pygmaeus Salter. X 1 

 (After Woodw. 1878, pi. XXVIII, fig. 5) 



that can be expected is that we shall find the Kokomo eurypterids 

 distinct from all those which lived in rivers on other continents. As 

 we shall see, the theoretical expectations are fully borne out by the 

 facts. 



The Eurypterid fauna of the Kokomo waterlime is distinct from 

 any of the known North American eurypterid faunas. The material is 

 never well preserved and the number both of species and of individuals 

 is small. " Stylonurus {Drepanopterus) longicaudus ," says Clarke and 

 Ruedemann, "is a unique form among the American eurypterids 

 being the sole representative thus far found on this continent of this 

 rare and phylo-genetically interesting genus. From its Scottish 

 allies, it is readily distinguished by its slender and elongated postab- 

 domen and the long, clavate telson." (39, 320) Four specimens are 

 known, two young and two mature individuals, and though they are 

 in sufficiently good condition to enable Clarke and Ruedemann to 

 make a restoration of the species, they do not approach the perfec- 



