450 L. G. JEakins — Two Sulphantimonites from Colorado, 



yet been found in the Laramie. But the generic form which 

 gives an especially unique character to the Puget fauna is that 

 of Batissa. This genus has not hitherto been known to occur 

 in North America, in either a fossil or living condition ; nor 

 has it been found nearer to this continent than certain of the 

 Pacilic islands. Still the hinge characters observable in these 

 Puget estuary specimens leave no room for reasonable doubt 

 that they are strictly congeneric with Batissa. Indeed a species 

 of that genus which is now living upon the Fiji Islands is 

 closely related to this fossil form. 



Certain interesting relationships between Asiatic and North 

 American faunas have been noticed by naturalists, which are 

 recalled by this occurrence of Batissa in the Puget fauna. As- 

 suming that these relationships are those of genetic succession, 

 we naturally desire to know the direction of the lines along 

 which their geographical dispersion took place. For exam- 

 ple, was it toward, or from the present North American con- 

 tinent that the dispersion of Batissa has occurred ? If if was 

 from this continent, it is remarkable that none of its pro- 

 geny have survived in any of the present continental waters ; 

 and it is equally remarkable that no evidence of its former ex- 

 istence in North America has "been discovered except that 

 which the Puget fauna has furnished. If the dispersion of 

 Batissa was toward this continent, it seems to have only 

 reached the present Pacific coast region about the close of the 

 Cretaceous period, and to have there and then become extinct ; 

 while it has continued its existence on certain islands of the 

 Pacific to the present time. But all the known facts concern- 

 ing the genus Batissa are insufficient to throw much light upon 

 its geological history or geographical dispersion. Even the 

 Corbiculidse, the family to which Batissa belongs has a less 

 completely known geological history in North America than 

 has the ITnionidse. 



Art. XLY. — Two Suljphantimonites from Colorado/ by 

 L. G-. Eakins * 



The mineral first to be described was sent to the Denver 

 laboratory of the U. S. Geological Survey in the latter part of 

 1885, by Mr. E. R. Warren, of Crested Butte, Colorado. 



At that time a hasty qualitative examination was made, estab- 

 lishing the fact that it was a sulphantimonite of lead, and since 

 then nothing more has been done with it until the present an- 

 alysis was made. 



*Read before the Colorado Scientific Society, Meeting of June, 1888. 



