KESPIKATORY OEGANS IN AllANEiE. 
41 
following folds occurring on the distal side of this one (i. e. 
exactly opposite to what takes place in spiders). The autlior 
does not appear to be cjuite certain about this point, and is, 
moreover, corrected by Pereyaslawzewa, who maintains that 
tlie oldest fold is the one nearest to the outer body wall (1 . e. 
as in spiders). 
Brauer’s text-hg. 15c (p. 413) very closely resembles my 
fig. IbB, so far as the ectoderm is concerned. He thinks 
there can be scarcely a doubt that the lung-book is not 
formed behind or apart from the appendage, but is the 
posterior half of the latter itself, which is invaginated and 
on which the pulmonary folds appear (p. 415). 
Laurie (’92) makes an interestiug statement regarding the 
position of the lung-septa in the older scorpion-embryos, 
Here they are placed horizontally, as in the older spider- 
embryos, whereas in the adult scorpion they are vertical 
(p. 102). 
Pedipalpi. — The development of the lung-saccules and 
their relation to the abdominal appendages do not appear to 
me sufficiently clear, from the existing embryological data, to 
make a comparison with the Aranese possible. Apparently 
the abdominal appendages are not so obvious in this group 
as they are in A ran e a) and Scorpiones, since the parts 
described by Laurie (’94j under this name are not identical 
with those to which Schimkewitsch (:06) applies the term. 
A remarkable point in the development, as described by 
ISchimkewitsch, is that the oldest saccules are said to be 
formed within the pulmonary sac and to subsequently migrate 
out of it ou to the posterior side of the appendage. In such 
a case their development would be exactly the opposite to 
tliat in A ran etc, as well as to what we should expect from 
phylogenetic considerations. 
Pereyaslawzewa’s (:01) descrijjtion of the formation of the 
lung-septa out of the cuticular wrinkles of the body-surface 
is altogether fanciful. 
The fully-developed lung-books of spiders. — A. Schneider (’92) 
has given an excellent account of the coarser anatomy of the 
