E. RAY LANKESTER, ON THE EARTHWORM. 7 
line are the largest on the plate, that at the outer or convex 
border being the larger. Indications of six other apertures 
exist, external and towards the convex outline of the shield. 
The three apertures in the articular end distinguish it from 
the eye-like slit of S. digitata. The shorter form of the 
anchor and the arrangement of the apertures distinguish this 
from all the other species of Synapta described. 
In conclusion, the author refers to his generalisation in 
his paper on the pedicellariz of the Echinodermata, that the 
anchor plates in the genus Synapta are the analogues of the 
pentagonal plates of the shell of Kchini proper and the anchors 
are spicula; but the analogues of the spines of Hchinide and 
Prasteridz organs for locomotion as well as defence, hookless 
to enable them to crawl out of their burrows. (See Plate I.) 
He also presents his kindest thanks to Professor Thomson, 
of Belfast, and M. J. P. Gallienne, of Guernsey, who have so 
generously placed these specimens at his disposal, and would 
propose 8. Thomsoniit for the Carrickfergus specimen, if not 
previously deseribed by any other naturalist. 
The Anatomy of the HartHworm. 
By E. Ray Lanxgrster. 
Parr IT, 
In the last number of this Journal the tegumentary, mus- 
cular, and digestive organs of the earthworm were briefly 
described, the form and structure of certain cesophageal 
appendages being more particularly noticed. The following 
pages will be devoted to the consideration of the Reproductive 
system, and of such secreting organs as are not of necessity 
connected either with it or the digestive system. 
Segmental organs.—This namewas proposed by Dr. Williams,* 
of Swansea, for certain organs which had long been known 
and appeared to exist in Annelides disposed in pairs in each 
segment of the body. These organs in the earthworm and 
the Oligocheta generally are in the form of tortuous ciliated 
canals, attached to the diaphragmatic muscles, communicating 
by one extremity with the exterior, and terminating at the other 
in a free, open expansion, on to which the cilia of the interior 
of the tube are continued. In the Limicole, the walls of the 
* ©Phil. Trans.,? 1858, 
