VEKMES. 13 



exception of the cephalic the whole of the segments differ 

 from each other in little else than their comparative calibre. 

 The integument is not hardened by the deposition of chitinous 

 or calcareous matter, and the appendages attached to the 

 different 'somites' are soft, and devoid of segments or of joints. 

 A typical 'somite,' from the middle region of the body, may 

 be said to consist of dorsal and ventral arcs each arc ter- 

 minates on each side in a conical eminence, constituting with 

 its appendages ('cirri' and 'setae') a 'notopodium' or 'neuro- 

 podium' according to the arc with which it is in relation. The 

 appendages attached to the * notopodium' are; first, a tuft of 

 branching caeca dorsally placed ; secondly, a fasciculus of 

 chitinous setse; thirdly, a small 'cirrus.' The neuropodial ap- 

 pendages are separated from the notopodial by a well-marked 

 interspace, and consist of, (1) a small fasciculus of setae, and 

 (2) a cirrus: but no branchiae. Towards the head and anal 

 extremity the branchiae become very small and are absent al- 

 together on the first two post-cephalic segments: and the setae 

 are also insignificant in size. The mouth and anus are ter- 

 minal: the former is situated on the ventral surface of the 

 third somite. 



22. A Common Earthworm (Lurribricus terrestris), dissected 

 to shew its digestive system. 



The transversely annulated integument has been divided 

 down the medio-dorsal line and pinned out on either side. The 

 digestive tract is seen in the middle line of the preparation, 

 and extends, without any convolutions, direct from mouth to 

 anus. 



The mouth (formed by a modification of the first segment) 

 leads into an oval pharynx, whose external surface has a 

 coarsely villous appearance, due to the breaking away of the 

 delicate muscular bands by which it was attached to the body- 

 wall. The oesophagus, in length about five-eighths of an inch, 

 and of much smaller calibre, leads from the pharynx to the 

 large and globular crop. Immediately succeeding this latter 

 cavity, and of slightly smaller size, and lighter colour, is the so- 

 called gizzard. Posteriorly to the gizzard the intestine is con- 

 tinued as a slightly sacculated tube of even diameter to the 

 anus. Attached to the oesophagus immediately anterior to the 



