NOTES AND MEMORANDA. 
245 
■ In the Nauplms larvse of Cyclops and Diaptomus the working 
is slightly different. The rectum is a subspherical muscular sac, 
which at regular intervals contracts so as to leave a linear cavity 
(along the long axis of the animal), and immediately dilates, 
sucking up the water from without. 
An anal respiration, such as that of Cyclops ^ is found widely 
among Crustacea — even those which have well developed gills 
like Astacus, which is one of the highest forms. It has been 
demonstrated in nyllopocla and Cladocera, and is 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 homoeomor- 
phic zooea larvae of the Decapoda will prove to have this same 
mode of respiration. 
If there be any connection between Eotifers and Nauplms, 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 ex- 
tension of chitinisation over the whole surface these organs lose 
their function and abort, while the cloacal contractile vesicle 
takes on an inspiratory as as well as an expiratory function, and 
becomes more or less confounded with the rectum, from which 
probably, even in Eotifers, it takes origin. 
Here must be noticed the wide diffusion of anal respiration in 
aquatic Insect larvee (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 : 
Rotifera. 
Gephyrea. 
Oligochceio Limicola, 
EcMnodermata, 
Tlolothuroidea. 
Arlhropoda. 
Crustacea (general). 
Insecta (most aquatic larvae). 
Mollusca. 
Bentalium, 
Dr. G. von Koch’s Method of Preparing Sections of 
Corals. — When working at the structure of corals during the 
Challenger expedition I found very great difficulty in deter- 
mining the exact relations of the hard to the soft parts. It is 
