1891.] Editorial. 559 
The other kind of “inexact parallelism” exists only in the brain 
of the student, and this is what chiefly troubles Prof. Vogt. It is 
always apparent when one attempts to compare things which 
should not be compared. 
If we compare, for instance, the embryologic record of a 
placental mammal with the adult non-placentals as they 
now exist, we will not get a parallel series, for the simple 
reason that both lines have long since abandoned their points of 
_ departure, and have added characters which were not present in 
their ancestors. The non-placentals are supposed with good rea- 
son to have been the ancestors of the placentals, yet the embryos 
of the latter, as is well known, do not possess marsupial bones nor 
inflected angles of the lower jaw. But it is also well known that 
a few existing Marsupialia do not possess either of these charac- 
ters, and it is generally admitted that some of the Jurassic Mam- 
malia resemble such Marsupialia most closely, and are probably 
the very ancestors for which we are looking. Andsoeverywhere. . 
It was expressly pointed out in the paper mentioned, that in 
order to find “exact parallelism” it is necessary to compare the 
species which form the same single line of descent; and that in 
proportion as our comparisons depart from this line, by so much 
will the inexactitude appear. As regards the Vertebrata, it will not 
be long before we will be able to present several Such lines, and 
ultimately many of them. In the lower animals the case will be 
more difficult as to their major characters at least, since these 
originated in such ancient geologic ages, and the structures them- 
Selves are generally so fragile, that some of the evidence must have 
been lost. “ Cænogeny” is, however, most especially seen in 
_ animals with long periods of metamorphosis. Here the larva has 
a life of its own, subject to the same classes of stimuli as those 
which affect the adult. But the history of these changes, when 
unraveled, will present the same parallelism between the primitive 
and later forms of larve as does the adult evolution itself—C. 
SOME important extra-American explorations have been recently 
undertaken by our citizens. The U. S. Fish Commission steamer 
“Albatross,” while on her way to the Pacific coast, recently con- 
ducted a series of sounding and dredging operations between the 
Central American coast and the Galapagos Islands, aided by 
