(32 
An anal respiration, such as that of Cyclops, is found 
widely among Crustacea— QY&n. those which have well 
developed gills like Astacus, which is one of the highest 
forms. It has been demonstrated in Phyllopoda and Glado- 
cera, and is here probably the exclusive mode in Leptodora, 
as shown by Weismann. That it is therefore primitive, 
and should be expected to occur in the primitive or at least 
very generalised group of the Copepoda, is an obvious 
deduction. Hence I anticipate that the homoeomorphic 
zooea larvae of the Decapoda will prove to have this same 
mode of respiration. 
If there be any connection between Kotifers and Nauplius, 
it is easy to make out the origin of the arrangement in the 
latter. The ciliated funnels and lateral canals of the former 
can only be of service when there is a thin unchitinised 
anterior surface through which water can transude into the 
coelom : by the extension of chitinisation over the whole 
surface these organs lose their function and abort, while the 
cloacal contractile vesicle ” takes on an inspiratory as well 
as an expiratory function, and becomes more or less con- 
founded with the rectum, from which probably, even in 
Rotifers, it takes origin. 
Here must be noticed the wide diffusion of anal respiration 
in aquatic Insect larvse, (alternate inspiration and expiration 
by the pumping movements of the rectum). This would 
point to a common origin with Crustacea. 
A list of the groups in which anal respiration is made out 
may be added. 
Vermes : 
Roiifera. 
Gepliyrea. 
Oligochoeto Limicola. 
Ecldnodermata. 
Ilolothuroidia. 
Arthropoda. 
Crustacea (general). 
Insecta (most aquatic larvse)* 
