THE EXOGONEiE. 227 



Integumentary and Pedal Glands. 



In E. fustifera the integumentary glands display a remarkable develop- 

 ment. In each segment near its posterior limit thev are arranged in a broad 

 zone (PI. 18. fig- 49) which is much more strongly marked on the dorsal side 

 than on the ventral. The secretion has a strong affinity for hematoxylin, 

 and in many stained specimens the result is the appearance of a very 

 characteristic pattern of transverse bands. The individual cells are irregular 

 in shape and of small size for the most part; but in the middle ventrally, 

 closely applied to the nerve-cord (see PI. 18. fig. 48 and lig. 50) are two 

 or three of considerably larger size — these groups of larger cells having the 

 appearance, in entire well-stained specimens, of dividing the nerve-cord into 

 lengths corresponding to the segments. 



In series with this zone of integumentary glands, but on a deeper level and 

 projecting into the ccelom from the body-wall, there are on each side in 

 the posterior part of each segment three larger rounded bodies (PI. 18. 

 figs. 44 & 45, i.gl. ; PL 18. figs. 41 & 42), each made up of a group of uni- 

 cellular glands with ducts opening on the surface about the lateral border 

 of the segment behind the parapodia. 



A feature of the glands last referred to which may be of physiological 

 significance, is the development within them, or some of them, of excessively 

 minute granules which pass out from the substance of the gland-cells into 

 the ccelom a^ definite corpuscles (PI. 17- fig. 29). 



The pedal glands are referred to by Malaquin (22), but only in the most 

 general terms. 



In Exogone fustifera the pedal glands are two pairs in each segment — 

 a dorsal and a ventral (PI. 18. fig. 49, r. />.//.), each placed in close relation to 

 the corresponding cirrus and partly contained within it. Of these the ventral, 

 situated for the most part just internal to the ventral cirrus, but extending 

 also into the interior of the latter, is of special interest since in the female 

 it is the gland secreting the viscid substance by means of which the ova 

 when discharged become attached to the parent. 



In E. verrugera the integumentary glands are not condensed into 

 transverse zones as in E. fustifera. They are fine convoluted tubules which 

 are most abundant in the anterior region of the body. The pedal glands 

 (PI. 18. fig. 36) are very similar to those of E. fustifera. 



In tiplicerosyllis hystrix the secretion of the integumentary glands forms 

 a resistant layer in which small particles of grit become thickly embedded. 

 This may be heaped over and around the papillae in such a way as to give 

 rise to the appearance of a system of comparatively large tubercles regularly 

 distributed over the dorsal surface. This does not soem to be of the nature 

 of a permanent laver since it varies greatly in thickness, and specimens are 

 sometimes met with in which it is entirely absent. This point has already 

 been referred to in the systematic part of this paper. 



