8 
Siphonophora rosarum 
intestine continues in its backward course until it approaches the 
posterior end of the body. It now makes a curve upwards and forwards 
and proceeds in an anterior direction into the region of the crop, and 
at the same time returning to the ventral surface, where it lies on the 
right side of the first portion. Having reached the region of the 
beginning of the crop, the intestine makes another upward curve and 
then proceeds backwards at the right side of the crop for its whole 
length. It then makes an abrupt curve downwards, at the same time 
encircling the crop, and appears eventually at the same level on the 
left-hand side. It now takes an anterior course and passes towards the 
region where the oesophagus joins the crop, but not quite so far as was 
the case on the right-hand side. Here it makes its final curve downwards 
towards the ventral surface, and passing through the loop formed by the 
first two coils, it takes a direct course to the anus. 
It is clear at once that there is a similarity between the alimentary 
canal in this stage and the apterous stage, but one which is more 
superficial than real. The main differences consist of the absence of 
the first coil present in the apterous individuals, and the curious 
complication of the second coil. It is difficult to see, on the one hand, 
■why the alimentary canal should have these curious coils in this stage; 
and on the other hand, why the elimination of the habit of flight should 
be coincident with such a rearrangement of the coils. It is quite 
conceivable, of course, that the form of the alimentary canal has no 
connection with the difference of habit, and may be due to other causes 
which are at present unknown. 
The mouth and mouth organs are almost exactly the same as in the 
apterous stage, the differences being very small and probably having no 
effect upon the functions of the various parts. 
The oesophagus offers no points for discussion beyond the fact that 
the lumen is perhaps relatively a little wider than it is in the apterous 
stage. 
The crop is perhaps a little longer in proportion to its width than 
it is in the apterous stage. The usual oesophageal valve, where the 
oesophagus enters the crop, is present. 
The coiled intestine varies very much in different individuals in the 
size of cross section and of the lumen. In many instances it resembles 
the coiled intestine of the apterous stage, but in some cases the lumen 
is reduced, in cross-section, to a star-shaped space in the centre of a 
rounded mass of granular material. These differences may be only 
post-mortem developments, but they are confusing. 
