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POPULAK SCIENCE REVIEW. 
tain the precise character of the bottom, special attention being paid to 
localities known to be the feeding grounds of valuable fishes, and to those 
animals upon which they are known to feed. It is believed that when the 
collections and notes made by the writer and his associates during previous 
years shall have been combined with those made during the past season, we 
shall have a tolerably thorough knowledge of the physical character and life 
of the bottom and shores in this region. 
The Life History of the Macropode has lately been given to the French 
Academy by M. N. Joly. The Lens ” [Jan.], commenting on the fact, 
states that eight years ago M. Agassiz said that he had found among the 
fish tribe metamorphoses as considerable as those which had been remarked 
in reptiles ,* and this is a case in point. The egg of the macropode, not 
bigger than a poppy seed, when hatched is perfectly transparent and lighter 
than water. It is hatched in about sixty-five hours, just as is the case with 
the egg of the tench. But on account of this rapid birth, the creature is neces- 
sarily in an imperfect state. It makes its appearance in the shape of a tadpole, 
the head and trunk of which are attached to a large belly, the tail being free 
and surrounded with a natatory membrane which is exceedingly transparent. 
Although the animal seems to have no striped muscular fibres, it is very 
nimble under the microscope, and is not more than a millimeter and a half 
in length. Its head has two large eyes still deprived of their pigment ; there 
is no mouth, and no digestive apparatus either. But the heart is already 
active, and some circulation is perceptible in the upper part of the tail. 
There are no gills, so that respiration must be effected through the skin. 
There are no secretory organs and no fins. The same as in all fish, the 
nervous system is formed at an early period, and is composed of two 
parallel cords, which branch out into the head. Of the skeleton nothing 
appears as yet but the dorsal cord. Numerous pigmentary spots appear 
all over the body. A short time after, the mouth, intestines, liver, and air- 
bladder are formed, together with the gills. New vessels gradually make 
their appearance, while the earlier ones are obliterated. The caudal 
natatory membrane is gradually formed into two pectoral fins, and brilliant 
scales cover the body, and from that moment the creature assumes the 
shape of a regular fish. Here, therefore, we have changes similar to those 
which are observed in Planer’s lamprey, in insects and in Crustacea. This 
is an important fact, since naturalists had hitherto denied the existence of 
such changes in fish. 
The Snakes of India. — We are glad to see that Dr. Fayrers’ fine work on 
this subject, which was much referred to in Professor Greene’s article in our 
last number of the Popular Science Review, has been very well received by the 
French Academy. The Academy appointed M. Dumas to review the book 
and state the results. This M. Dumas has done in a short but most favour- 
able notice which is published in the Comptes Rendus ” (February 24, 1873). 
Philadelphia Academy of Sciences. — When the new building is complete, the 
fine collection will be displayed to the general public. We understand that 
it has now in its possession, though of course not under public view, more 
than 6,000 minerals, 700 rocks, 65,000 fossils, 70,000 species of plants, 1,000 
species of zoophytes, 2,000 species of crustaceans, 500 species of myriapods 
and arachnidians, 25,000 species of insects, 20,000 species of shell-bearing 
