58 Mr. H. M. Bernard on the 
the Crustacean gland would then be, what it clearly is in 
Galeodes, a development of the proximal end of an originally 
simple tubule, and not, as is often suggested, a modified 
portion of a primitive coelom. 
The establishment of this point would be one more argu- 
ment in favour of my view that the antennal and shell-glands 
of the Crustacea are probably derivations of acicular or seti- 
parous glands*, It is interesting tonote that a similar sugges- 
tion had already been made by Hisig } with regard to the 
origin of the coxal glands of the Arachmnids. 
In both cases (¢. e. in Crustacea and Arachnida) we should 
then have setiparous glands gradually specialized for excretory 
purposes as the primitive nephridia became specialized into 
genital ducts. The extreme plasticity of the setiparous glands 
is well known—slime-glands, spinning-glands, and poison- 
glands being generally deduced from them ; further, tracheal 
invaginations and salivary glands may also with great proba- 
bility be traced back to them. That some of them should 
have become specialized for excretion is not improbable. 
Without enlarging any further on this suggested deriva- 
tion of the antennal and shell-glands of the Crustacea and the 
coxal glands of the Arachnida from sctiparous sacs, I should 
like to point out a remarkable physiological connexion which 
appears to exist between the different kinds of Arachnidan 
glands. Galeodes has no spinning- or poison-glands, but 
highly developed coxal glands and Malpighian vessels. 
Scorpio has well-developed stinging-glands, which, however, 
are but occasionally employed, and well-developed coxal 
glands and Malpighian vessels. The Chernetida have very 
large true spinning-glands and modified spinning- (cement-) 
glands, which are periodically developed. ‘They have, further, 
coxal glands, but no Malpighian vessels. In these animals 
we have to bear in mind that the spinning- and cement-glands 
are not always functional, so that some purely excretory 
apparatus for the direct removal of waste products is required 
during those times when these excretory matters are not being 
utilized for the formation of silk or cement. 
In the Araneide we have, as a rule, a perennial flow of silk 
and a consequent degeneration of the purely excretory glands. 
The coxal glands have, as a rule, degenerated, while the 
Malpighian tubules no longer come in contact with the blood- 
stream, but ramify through the peritoneal cells which bind 
the numerous diverticula of the mid-gut into a solid mass, 
* ©The Apodide’ (Macmillan, 1892). ; ‘a 
+ Eisig, ‘Die Capitelliden des Golfes yon Neapel’ (1887). 
