Z00u0gy- 245 
can be maintained, with our present knowledge of the former, as a 
natural group, while it has been fully shown by the anatomical 
researches of A. Milne Edwards and others that Zimulus is not a 
Crustacean, in any proper sense. The Pycnogonida have also 
been badly treated, for this group, remarkable for so many 
anatomical and morphological peculiarities is dismissed in three 
lines (p. 360), as a family of mites! But the Pycnogonida would 
t 
this peculiarity in a marked degree and have long ago been so 
described in the works of L. Agassiz, A. Agassiz, and others 
Hybocodon prolifer Ag., and Dysmorphosa rans are notable 
ence to the breeding of the “dogfish,” for on the former pase it 
18 said that they lay eggs, while on the latter page “ the dog-f 
(Squalus A mericanus)” is mentioned. The latter produces living 
young, as well as the Mustelus canis. A. . 
: System der Medusen (Erste Halfte des ersten Theils : 
System der Craspedoten); von Dr. Ernst HACKEL, 1x and 
360 pp., with 20 plates. Jena, 1879.—Since the publication of 
Eschscholtz’s System der Akalephen, an — number of addi- 
