72 MR WILLIAM TURNER AKD DR H. S. WILSON ON THE 



portions which connect the different pairs of cceca vary in length in dif- 

 ferent animals. The canal ends posteriorly in a blunted, rounded cul-de-sac, 

 which lies between the last pair of coeca. This small terminal part Rathke has 

 described as an intestine ; and he considers that it opens externally by an anus. 

 We have looked in vain for such an opening, and must therefore conclude that it 

 does not exist, a conclusion to which Claus also had arrived. Moreover, it is quite 

 possible to remove the whole alimentary canal from the visceral cavity, so as to 

 see clearly that it has no connection with the surface except at the oral aperture. 

 The wall of the whole of the canal, except the oesophagus, presents a number of 

 small dilatations, which give to it a very irregular aspect. These are formed by 

 the protrusion of the lining membrane of the gut between small polygonal spaces 

 due to the crossing of the longitudinal muscular fibres of the canal by transverse 

 and oblique fibres. We could not see any indications of transverse markings 

 in these fibres, although Claus states that he has seen distinct striations in 

 them. A quantity of (by transmitted light) dark brown granular matter is 

 contained in the canal, especially in the dilatations on its walls. 



We cannot say anything definite from our own observations as to the existence 

 or position of a heart, although Rathke describes as such a thin canal, pointed 

 at both extremities, situated just behind the neck. During an examination of a 

 living specimen, we thought we observed, on one occasion, a movement in the 

 interior of the margin of the fourth thoracic segment, which might be due to a 

 circulatory fluid. Rathke also describes on the abdominal aspect two nen^ous 

 cords with proportionately large ganglia, but we were unable to detect any such 

 structures. The animal possesses a very complete muscular apparatus for the 

 movement of the antenna^ hooks, jaws, and limbs; and in addition muscular 

 bundles extend in a longitudinal direction along the ventral and dorsal aspects, 

 especially the former. The fibres possess a delicate but ver}' distinct transversely 

 striped appearance. 



A complicated system of branched and communicating tubes is situated on 

 each side, in the visceral cavity of the animal, external to the alimentary canal. 

 This tubular arrangement is the ovary. It extends not only into the lateral pro- 

 cesses from the sides of the thoracic portion, but even into the dorsal and ventral 

 median processes and into the thoracic feet, all of which are hollow, and commu- 

 nicate with the interior of the visceral cavitj^ Some of the tubes commence 

 by rounded, others by finely pointed ends (fig. 10). Many exhibit a very con- 

 voluted arrangement. They open on each side into a tube which runs parallel 

 to the intestine, and which is more or less concealed by the gut. This tube is the 

 oviduct, and it extends backwards as far as the proximal segment of the ab- 

 dominal division of the animal, where it opens. The opening is protected by a 

 chitinic plate, folded inwards on itself towards the mesial line. This folded plate 

 has very much the appearance of a bivalve shell. Just before it opens, it is 



