88 
REVIEWS. 
nopoda. We would mention a paper by Krohn on tbe heart and cir¬ 
culation in Pycnogonidae. This organ, the existence of which has been 
negatived by Quatrefages, was demonstrated by Zenker in Nymphon 
padlipes. A very particular account of its structure and of the pheno¬ 
mena of circulation is.given in this essay, which will be found in 
Wiegmann’s “ Archives” for 1855-56. On the order of Pseudoscor- 
piones, we have a very elaborate memoir by Menge; he gives a very 
full and elaborate account of the internal and external anatomy of this 
minute tribe. He divides the family into five genera, and enumerates 
fifteen species, of which seven are found in amber, and eight recent. 
Vide “Transactions of the Dantzig Society of Naturalists,” vol. v. part 4, 
1855. 
To the many memoirs on the Scorpions, we must add one by Dufour, 
which appeared in the “ Memoires presentes par divers Savants a l’Aca- 
demie des Sciences,” &c., vol. xiv., 1856. This essay, based on the 
examination of nine different species, under circumstances more fa¬ 
vourable than preceding observers could command, offers, doubtless, the 
most complete and trustworthy account that has yet. .appeared of the 
structure of this family, which is peculiarly interesting from its highly 
complicated organization, and because of the light it throws upon the 
rest of the class, in which the parts become more crowded and con¬ 
founded, so as to disguise their homologies. Dufour, having traced the 
origin of the nerves which supply the mandibles and chelipalps to the 
thoracic ganglion, accordingly denies the existence of antennae in this 
tribe, and, by inference, in the rest of the Arachnida. He impugns the 
propriety of the generic divisions which have been founded on the num¬ 
ber of the eyes ; he maintains that three ocelli on each side is the con¬ 
stant number in various species to which more than this have been 
attributed ; and he states the curious fact that, in the Scorpio JEuropceus, 
which has but two at each side when full grown, there are three with 
their distinct optic nerves in embryo, but two of these contiguous, and 
one of them subsequently disappears by abortion. 
Passing on to the Crustacea, our attention is arrested by the very 
meagre account we get of their metamorphosis, if we except a few lines 
added by the translator from Darwin. The whole subject is dismissed 
in about half a page, and in this short space many errors, both of omission 
and commission. No reference is made to the fact that Zoea taurus was 
figured and described as far back as 1778 by Slabber, a countryman 
of our author; and we are informed that it is to John Thompson, an 
Englishman, that science is indebted for the discovery of the change of 
form in Decapods. 
To the bibliography of the family Ostracodea add a new memoir by S. 
Eischer, in the “Transactions of the Eoyal Bavarian Academy of Science,” 
vol. vii. Yan der Hoeven (differing from Erichsen and others) consi¬ 
ders the two large jointed appendages, especially useful in swimming, as 
posterior antennae. There is an interesting paper by Lievin, in the 
“ Transactions of the Dantzig Society of Naturalists,” vol. v. part 4, on 
the “ Dud” or Eezzan worm, the Artemia oudneyi of Dr. Baird; this 
