532 Wisconsin Academy of Sciences, Arts, and Letters. 



Species. One must expect more of these abiLorm.alities to 

 be found in those species native to regions where most atten- 

 tion is paid to the fauna and also in the most abundant spe- 

 cies. Yet after making these corrections, it is probable that 

 this axial bifurcation is more frequent in some species than in 



others. 



Tabulating the data, we find: 



Tro2ndo7iotus. 



3 T. fasciata sipedon Linn. 



2 T. natrix Linn. 



1 T. fasciata fasciata Linn. 

 5 Bascanium coistrictor Linn. 



3 Eutainia. 



2 E. sirtalis Linn. 



1 E. elegans lineolata Cope. 

 2 Ophiholus getulus Linn. 

 2 Pelias herus Merr. 

 2 Pityophis. 



1 P. catenifer Blainv. 



1 P. sayi Schlegel. 

 1 Ancistrodon piscivorus Lacepede. 

 1 Pelamis hicolor. 

 1 Lachesis lanceolatus ( ?) 

 1 IIeterodo7i simus Linn (?) 

 1 ^'Yellow snake of Barbadoes.'' 



This result together with Mr. Garman's statement concern- 

 ing Tropidonotus would seem to make it advisable to examine 

 gravid snakes of the genus Tropidonotus and eggs of Basca- 

 nium if in search of this abnormality. 



Type of Bifurcation. The great majority of cases are 

 those of cephalic bifurcation, the catadidyma of Fisher. 

 !N^one show merely caudal bifurcation, the anadidyma of 

 Fisher. But three cases have been described where both 

 cephalic and caudal bifurcation existed, the anacatadidyma 

 of Fisher. Tliese are the case of Wyman and t^vo of tlie three 

 described by Mitchill. The former's* specimen is further re- 

 markable for a median duplicity of the vertebral column, 



