1885. J NEW-ZEALAND EARTHWORMS. 817 



§ Alimentary Canal. 



The alimentary tract of Acanthodrilus, as of other Earthworms, 

 consists of a straight tube passing from the ventrally placed mouth 

 at the anterior extremity to the terminal anus ; it is specialized into 

 several distinct regions. 



The buccal cavity passes almost immediately into a large vyiJe 

 pharynx, which is attached to the body- wall by a mass of muscular 

 bundles of various thickness ; in the pharyngeal region the mesen- 

 teries, which posteriorly limit the segments, are no longer recog- 

 nizable, but have become metamorphosed into this mass of muscles. 



In A. dissimilis, and probably also in A. novcB zelandice, a 

 quantity of glandular tissue lies on the dorsal surface of the 

 pharynx between the muscular fibres, which, no doubt, represents 

 a sahvary gland such as that which Perrier has described in 

 Pontodrilus. I have been unable, however, to make out the ducts 

 of these glands. 



In A. multiporus there are also salivary glands, which I am 

 inclined to think are morphologically different from those of 

 A. dissimilis. At the sides of the pharynx in segment 4 (Plate LIU. 

 fig- 4, gl) are a pair of large arborescent glandular masses ; the tubules 

 which compose the gland of either side unite to form a slender duct {d), 

 which is accompanied by a blood-vessel giving off capillaries which 

 ramify over its walls. I traced the duct as far forward as the circum- 

 oesophageal commissure ; at this point it passed under the commissure 

 to open out the buccal cavity by a very conspicuous orifice (see fig. 5, o). 

 The three anterior segments of the body occupied by this pair of 

 glands and their ducts have no nephridia; and as the structure of these 

 glands resembles exactly that of the nephridia, there is little doubt 

 that they are the slightly modified representatives of the nephridia 

 of these segments ; the most anterior nephridia were in the fourth 

 segment, i. e. the third in front of that which contains the most an- 

 terior pair of copulatory pouches. Each gland consists of a multitude 

 ofcsecal (?) tubes accompanied by an abundant supply of capillaries. 

 Distally, the gland-tubules consist of rows of perforated cell quite 

 similar to those of the distal section of the nephridia in Lunibricus 

 &c. ; this portion of the tubule forms a complicated coil. Where the 

 tubules unite together the character of the epithelium changes, and 

 the duct comes to be surrounded by a row of cells instead of being 

 contained within the substance of the cell. As the glands open 

 into the buccal cavity, they may be termed salivary glands ; they 

 appear to correspond to the "glande a mucosite " described by 

 Perrier in the genus Urochata ' : there are two of these glands 

 situated in the anterior region of the body, each opening by its own 

 duct on to the exterior in the third segment. liike the salivary 

 glands of Acanthodrilus, the mucous, glands of Urochceta have 

 precisely the same structure as the nephridia ; and the fact that the 

 latter are wanting in those segments of the body which contain the 

 glands and their ducts is an additional argument for supposing, as 



' Arch, de Zuol. Exp. t, iii. p. 439, pi. svi. figs. 35, 37, 43. 



