J Recent Literature. 513 
the lightest coke, the vesicles, however, being considerably 
er than those of the ordinary coke, and very uniform through- 
The septa between the vesicles are very thin, and the whole 
š is so light that wh .,|,., xecimen is varnished over to pre- 
access of water to  .3-.vities, it floats upon water like a 
* * * Any a... ipt, however, to fix the age of these 
> must prove quite fruitless. All that we can say is, that it is 
fecent, even when time is judged by the historic or human 
dard. It cannot be many centuries old, and it may be more 
the Spanish conquest. But there are reasons why 
wi regard chiefly to the action of running water and 
ang, will this volume possess permanent value. 
~y necessary to add that the pencil of Mr. Holmes, 
genus t sketching geological panoramas is almost unique, 
r 
with the illustrated paper which bears the second of 
1 below, and as a possible prodromus of others, it 
tion. The system of the Bulletin No. 1 of the Na- 
m (which is devoted to this subject) has been so gen- 
-= oy American herpetologists that it becomes neces- 
800d reasons should be adduced for the many dif- 
which the present system and list present. These 
ot been given, so far as we are aware, and we think 
nat none can be found. 
“sa these papers has clearly not been equipped for 
has undertaken. In the systematic department he 
Pecies ocurrin, north of the Isthmus of Tehuantepec, with refer- 
etin of the Essex Institute Salen Jan» 1884, On th 
