
500 THE AMERICAN NATURALIST. [VoL. XXXVI. 
described. The posterior so-called “anal pit” is said by Ikeda to 
be the Anlage of the nephridia, and to have no connection with the 
so-called “primitive streak." In many details Ikeda's results differ 
from those of Masterman, — especially in many of the points which 
the latter emphasizes as indicating affinities with the Diplochorda. 
Thus, Ikeda considers as artefacts, due to reagents, the oral and 
pharyngeal grooves which Masterman had compared with gill slits, 
the *neuropore," the *subneural gland," and certain parts of the 
vascular system described by Masterman. He was further unable 
to find the * proboscis pores " of Masterman, the “trunk nephridia," 
the ventral blood vessel, the dorsal mesentery, the collar nerve ring, 
the ventral nerve commissure, or the perianal nerve ring. The 
impression is thus given that his results are largely opposed to those 
of Masterman; the latter, however, points out in a recent review’ 
of Ikeda's paper that in regard to the fundamental structure of 
Actinotrocha the points of agreement are more important than those 
of disagreement; indeed, he claims Ikeda's work as a corroboration 
of his own. 
Ikeda has given especially valuable observations on the relation 
of the body cavities and vascular systems of the adult to those of 
the larva, — a complex matter, on which little had been done, and 
which perhaps requires still further elucidation. The vascular 
system of the larva is very simple as compared with that of the 
adult, not forming a closed system at all; the transformation of the 
one into the other in the fifteen or twenty minutes occupied by 
the metamorphosis is therefore a complicated matter. In the same 
way the body cavities of the larva and adult by no means correspond. 
Ikeda states that the collar cavity of the Actinotrocha is largely 
transformed into the “ring vessel" of the adult, — the collar cavity 
of the latter being largely a new formation. HSI 
A General Course in Insect Anatomy.? — This is a new edition of 
a little book that is important both of itself, and because it represents 
the fundamental laboratory course in the chief center of entomologi- 
cal instruction in America. The book has been evolved along with 
the laboratory which it represents, and each new edition marks 
Progress in the knowledge of even those subjects which are dealt 
with in the most elementary instruction. 

1 Quart. Journ. Micr. aps vol. ve (1902), pp. 485-492. 
? Comstock, J. H., Kellogg, V. L. The Elements of Insect Anatomy: An 
Outline for the Use of uae, in i Msi! Laboratories. Ithaca, Comstock 
poner: Co., 1901. 145 pp., 11 figs. 

