422 SIR WILLIAM TURNER 
halves by a broad mesial mesentery formed of non-striped muscle. The walls of the 
dorsal and ventral spaces were lined by cells like those previously described. Strong 
striated muscles were situated laterally to the intestine; they arose from the wall of 
chitin, and were inserted by tendinous bands into the wall of the gut. Processes 
of the highly pigmented lining membrane passed between bundles of these fibres, and 
differentiated them into distinct muscles. 
At the anus itself the dorsal and ventral spaces were scarcely to be recognised ; the 
lumen of the intestine was small and laterally compressed. The submucous coat was 
greatly thickened aud the mucous membrane showed no parallel ridges. The lateral 
striped muscles were well marked. ‘The dorsal and ventral mesial bands of non-striped 
muscle were prolonged on to the sides of the intestine, external to its proper coat, and 
were arranged in an ellipse. At and near therefore the anal orifice the intestine was — 
provided with transversely striped muscles, situated laterally, which acted as dilators ; 
and with non-striped muscular fibres, distinct from the proper muscular coat, which 
formed a sphincter muscle (fig. 19). 
No specially differentiated VascuLar SysTEM was recognised, and no structures 
that could be regarded as heart, blood- or lymph-vessels. The dorsal and ventral — 
spaces associated with the alimentary canal, and the intervals between the bundles 
of fibres of the mesenteries and of the lining membrane of the chitinous wall, 
provided channels for the distribution of a nutritive fluid. 
Nervous System. 
In the section on the structure of the head I have described the pair of 
cesophageal ganglia, which, from their size, constituted the most important divisions — 
of the nervous system. Their relation and structure having already been narrated, 
it is unnecessary to repeat them; but it may be stated that the position of the — 
ganglia enabled them readily to supply nerve fibres to the wall of the cesophagus — 
and to the striped muscular fibres, which formed important constituent parts of 
the head. Associated with the ganglia was a relatively large nervous cord, composed 
of numbers of delicate nerve fibres. 
In transverse sections through the elongated thoracic segment clusters of cells — 
were seen at intervals in close relation to the pigmented lining membrane of the — 
ventral part of the wall of chitin and to the ventral space. The cells coloured — 
readily with carmine, and the nuclei stained deeply and were relatively large. In 
some sections at least one process could be seen to arise from the cell body; in 
others a process arose from opposite aspects of the cell body, and the cells appeared 
to be fusiform or bipolar; other cells, again, were multipolar, and with delicate 
processes extending for a recognisable distance. In one specimen a process could 
be traced so far undivided as to be obviously the axon of the cell. Hach cluster 
of cells formed a small nerve ganglion, the cells in which were smaller than in 
