390 E. S. GOODRICH. 



dorsal line. As for the extension of the organ at its ventral 

 border, fig. 4, which represents the middle portion of the sagittal 

 section through two segments, shows that it reaches halfway 

 across the segment from near its posterior limit (figs. 2, 4, 

 dors. cil. org.). The surface of the organ is much folded, 

 especially the outer limb. 



The finer structure is shown in figs. 4 and 6. In the former, 

 which was taken from a section stained in borax carmine, tlie 

 cells are seen to have indistinct walls and to be somewhat 

 striated on the outer edge, which is very darkly staining. The 

 nuclei are large and more or less oval in shape. Fig. 6 repre- 

 sents a small portion of the organ, taken from a section very 

 similar to the right side of that shown in fig. 5. This section 

 has been stained with hsematoxylin, and shows no distinct cell 

 outlines. The protoplasm in which the nuclei are embedded is 

 slightly granular within, and under a high power (Z. 2 mm. horn, 

 oil im. and oc. 8) appears to be divided up into chambers, as it 

 were, by the minutest ramifications of a network of darkly 

 staining substance very similar to that described below in the 

 nephridium. Towards the inside this substance forms the 

 thin limiting membrane (PI. XXXIV, fig. 6, /. mb.) which lies 

 on the muscle, while towards the free surface it forms a dark 

 zone (fig. 6, d. z.), and then the dark lines which give the 

 outer edge of the organ its striated appearance. Outside this 

 striated layer, at the very surface, the darkly staining substance 

 forms a cuticular layer (fig. 6, cut.). The surface is beset with 

 fine cilia (fig. 6, cil), the bases of which, perhaps, are con- 

 tinuous with the light portions of the stria? in the underlying 

 substance. On every side the epithelium forming the organ 

 is continuous with the coelomic epithelium, of which it is, in 

 the adult at all events, a highly modified patch. It is quite 

 clear from these descriptions, I think, that the dorsal ciliated 

 organ shows no trace of a glandular structure. 



In conclusion, I may say that this organ is present in every 

 segment of the body from the tenth, except the last two, in 

 which the nephridia appear to be also absent. It occurs in both 

 sexes, and I have found it in every member of the family which 



