ON TWO NEW GENERA OF AQUATIC OLIGOCH.ETA. 297 



Septal Glands. — A few Oligochseta are provided with peculiar glandular structures 

 attached to a certain number of the anterior intersegmental septa, which are usually 

 regarded as glands appended to the oesophagus. They have been hitherto found in the 

 Enchytrseidse, in some Naidomorpha, and in Phreatothrix among the Lumbriculidee. 

 They occur also, as I have already pointed out in this memoir, in my new genus 

 Phreodrilus. 



The septal glands are found in segments V-VII ; they form a series of paired structures 

 lying on the anterior face of the cup-shaped septse which lie between these segments. I 

 could not find any evidence of their possessing a central lumen such as has been described 

 by various writers. In all my sections the septal glands were undoubtedly solid structures, 

 though often furnished with a fibrous core. The cells which compose these glands appear 

 to have no particular arrangement. They have a glandular appearance, and are pear- 

 shaped. The extremity of the cell passes into a fine prolongation ; the prolongations of 

 all the cells unite to form solid strands, which are bound up in a darkly staining sheath, 

 which is continuous with the sheath of the gland. The fibrous core that has been 

 mentioned is simply produced by the processes of these cells. In fig. 36 I have sketched 

 a portion of one of the septal glands showing the fibrous core, which is really a bundle 

 of the ducts of the unicellular glands, which are associated together to constitute the 

 septal glands. The fibrous core passes forward towards the pharynx, and then gives off 

 branches of various sizes, which end in close contact with the basis of the epithelium of 

 the pharynx on the dorsal side. The dorsal blood-vessel is also shown in the figure 

 lying just above the " apertures " of the septal glands. The fibrous strands which 

 connect the septal glands with the pharynx have a few nuclei interspersed. It appears 

 to me that, at any rate in this Annelid, the septal glands are simply to be regarded as 

 masses of unicellular gland- cells — each gland-cell being prolonged into a duct which 

 reaches the pharyngeal epithelium. 



The structure of these glands, in fact, is very much like that of the " capsulogenous " 

 glands in Perichceta. In many species belonging to that genus — probably in most — there 

 are little, white, pear-shaped, glandular bodies opening on the ventral side of the body in 

 the neighbourhood of the reproductive apertures — both the vasa deferentia and the 

 spermathec£e. # The structure of these bodies is very simple ; they consist of groups of 

 unicellular glands bound together in a common sheath, whose ducts can be traced through 

 the epidermis to the exterior. In Pelodrilus I must confess to having been unable to 

 trace the ducts of the septal glands through the pharyngeal epithelium. They appeared 

 to end at these bases of these cells. I am, nevertheless, decidedly of opinion that the 

 septal glands should be referred to the same category as the integumental glands of 

 Perichceta, and that both structures are seen in their least specialised condition in the 



* I notice that Eosa, in a recent paper, still speaks of the small second appendage of the spermatheca in 

 Perichceta Houlleti (and P. campanulata) as a diverticulum of the spermatheca. If the structure of the body in question 

 is the same in Perichceta campanulata as in the species which I investigated, and believed to be identical with 

 Perrier's P. Houlleti, the term is hardly applicable. 



VOL. XXXVI. PART II. (NO. 11). 2 Y 



