92 
W. F. PUrx’CFI.L. 
Thus the homologies of the abdominal appendages in 
Limulus may with the greatest probability be represented 
as in the table on p. 86. 
XL Historical List of Papers concerning the Lung- 
books OF Arachnids (Exclusive of those Dealing 
ONLY WITH Enervation, Embryology or Theoretical 
Considerations.^) 
Meckel (’09 and ’10) gives the earliest anatomical descrip- 
tion of the lung-books of a scorpion and spider. He observed 
the leaflets (saccules) attached to a stalk (pedicel and ante- 
chamber) leading to the spiracle, and thought the stalk might 
be hollow. He looked upon the organ as a real gill-book. 
Gr. K. Treviranus (’12, ’16) describes the lung-books of 
scorpions and spiders (as true gills) and the interpulmouary 
fold and its muscles in spiders. He thought the “gills” may 
be mainly organs for absorbing moisture from the air, while 
the respiratory functions are carried out principally by four 
jiairs of stigmata on the back of the abdomen (muscle 
impressions) and four pairs on the sides of the cephalo- 
thorax. 
H. jM. Gaede (’23) describes the four lung-books of a 
My gale (as gills) and observed the “granulation” on the 
leaves. He thought tlie respiration took place, not in the 
“gill-leaves,” but on the fine membrane behind them (i . e. 
on the posterior wall of the ante-chamber, which is smooth 
in some Tetrapneumonous spiders, e. g. in Cry])sidromus 
inter m e d i u s) . 
Johannes Muller (’28a, ’28b) discovered that the stalk 
(pedicel), ante-chamber and leaves (saccules) in scorpions 
and spiders are hollow by blowing air into the spiracle, and 
so proved the pulmonary function of the lung-books. He 
‘ The coiuiiarative anatomy of the lung-books is outside of the scope 
of this paper, so I give this list in the form of an appendix for the use 
of future workers on the subject, as it is more complete than any list 
yet given. 
