1885.| Zoology. 185 
proved by the fact that eviscerated specimens in which the con- 
nection of the sub-epithelial bands with each other was destroyed, 
were capable of executing these movements. The axial cords 
act both as afferent and efferent nerves. LEvisceration causes 
apparently but little inconvenience to the animal, and the visceral 
mass is regenerated completely in a few weeks. The apparent 
morphological difference between the nerve system of the Crin- 
oidea and of other echinoderms disappears upon examination. 
Taking the Asterids as the lowest term of the series, it will be 
found that in those creatures, as shown by Hamann, nerve fibrils 
are found over the entire dorsal surface of the animal. While in 
Ophiurids, Echinids and Holothurids the ambulacral portion of 
the continuous nervous sheath of the star-fish has concentrated 
into a well-defined cord, the remainder being absent; in the 
crinoids the ant-ambulacral or dorsal part being continuous 
nerve-sheath of the star-fish has developed into the so-called 
axial cords, and the ambulacral bands also subsist as a subordi- 
nate nerve-system. 
HERRICK’S CLADOCERA AND COPEPODA OF MinneEsoTa.’—In this 
excellent report we have for the first time a summary of the 
known genera and species of all our fresh-water, free-swimming 
Entomostraca with the exception of the Ostracodes. It will 
prove not only useful but stimulating to our inland naturalists. 
As a pioneer work it is entitled to much credit, since many of 
our species are identical with those of Europe, and much care is 
required in the generic and specific descriptions, since the distinc- 
tions are based on such slight characters. In the introduction 
the author shows how important these micro-crustaceans are as 
scavengers, and in what astonishing numbers they exist, 1442 
specimens occurring in a quart of filthy pond water. 
The discussion of the affinities and genealogy of the Clado- 
cera is interesting ; this is’st led by an account of the lead- 
ing works on them. The order, families and genera are charac- 
terized with sufficient fullness, and a tabular view of the classifi- 
cation of the Cladocera is given, as well as useful keys to species 
under each genus. Under the family Daphnide a long account 
of the circulatory system is given from original observations, 
The Copepoda are treated in the same manner as the other order, 
and all the species collected by Mr. Herrick or previously known 
are described, but why no description of Canthocamptus tenuicau- 
dis, n. sp., is given, we hardly understand, though it is figured, 
while C. cavernarum Pack., from Mammoth cave, is not men- 
tioned. The number of species of Copepoda seems meager, and 
1A final report on the Crustacea of Minnesota, included in the orders C ladocera 
and Copepoda. Together with a synopsis of the described species in North Amer- 
ica, and keys to the known species of the more important genera. By C. L. Her- 
rick. From the twelfth annual report of the Geological and Natural History Sur- 
vey of Minnesota, 1884. 8vo, pp. 191, with 29 plates, ; 
