834 ` General Notes. [August, 
and M. de Meuron is convinced of the existence of an internal 
orifice furnished with. vibratile cilia directed backwards. The 
true kidneys in the same genus are composed partly of an ecto- 
dermal invagination, and partly of mesodermal structure. The 
two parts unite early and so closely that they cannot be distin- 
guished. The kidney then increases rapidly and takes the shape 
of the letter S, one extremity terminating at the bottom of a fold 
of the pallial cavity, while the other opens into that of the peri- 
cardium. M. Grobben considers the cavity of the pericardium as 
the remains of the primitive cceloma, but M. de Meuron sees in it 
the cavity of the posterior of the two somites of a mollusk. The 
primitive kidneys thus represent the excretory organ of the first 
somite; and the true kidneys that of the second somite——Pro 
fessor H. L. Osborn (Stud. from the Biol. Lab. J. Hopk. Univ), 
gives an account of his studies upon the structure and growth of 
the shell of the oyster. A thin circular glass was inserted be 
tween the outside of the mantle and the inside of the shell, and 
the secretion examined. After twenty-four hours a thin gummy 
deposit, with in some cases a few lime crystals, was found, This 
was clearly a viscid secretion from the surface cells of the mantle. 
brown membrane, like the epidermis of a shell, but containing 
calcium carbonate in solution. A film six days old had lost 1s 
leathery character and become strong, and after three or four 
weeks the glass is completely coated with white shell, principally 
formed of the mother-of-pearl layer. w 
Crustaceans —The Challenger report upon the Cirripedia 8 
by Dr. P. P. C. Hoek. Seventy-eight species are rep 
fathoms. Forty species of Scalpellum were added by the ee 
er 
Ten es ol 
bution of this genus 
of i ay ; 
The Challenger report of Dr. S puding 
mostraca, chiefly Copepoda, and the cold waters of the Pha 
gions seem even more favorable to these animals than trop a 
