Alhneatary Si/stem of GnjUota^Ki australis. 115 



It possesses two diverticula, viz., two pairs of 

 arborescent glands (Dufour), and the urinary or 

 Malpiijhian tubes. 



Salivary Glands. 



A detailed description of the Salivary Glands of G. vulgaris 

 is given by Bordas (1). There is no fundamental difference in 

 G. australis. Briefly stated they are composed of two pairs of 

 bunches of lobules, and two thin walled and extensible reservoirs. 

 The smaller efferent ducts, and tlie ducts from the reservoirs, 

 open into main ducts, which traverse the prothorax on each side 

 of "the oesophagus, pass below the ganglia, and meet to form a 

 very short common duct that opens behind the lower lip and 

 under the lingua. Of the two pairs of bunches of gland cells, 

 the anterior pair, located in the mesothorax, is the smaller; they 

 in part meet and surround the oesophagus. 



The posterior pair, situated principally in the metathorax, is 

 larger, and, in contrast with Bordas's experience, I have generally 

 found them to stretch as far back as the second abdominal 

 segment, a little anterior to the testes. 



The cells of the alveoli are surrounded by a thin cellular 

 membrane. The nuclei of the secreting cells are large (25/a) 

 and possess numerous nucleoli. 



The whole of the glands and ducts originate from the 

 ectoderm. 



Fope-gullet. 



The fore-gullet, leading from the pharynx passes through 

 the occipital foramen and following a straight course through 

 the thorax opens, at a distance of 14 mm., into the crop. When 

 not distended by food its lumen is closed by deep longitudinal 

 folds, but it is capable of very wide distension. Its outer wall 

 (Fig. 2) is composed of annular and longitudinal muscle fibres 

 (I have not determined a peritoneal layer), overlying a thin 

 basement membrane, upon which repo.ses a single layer of cubical 

 epithelial cells with large nuclei ; these secrete a thick layer of 

 hyaline chitin, bordered by strong yellow chitinous denticulations. 

 These teeth (Fig. 2a), are "2 mm. in length, laterally much 



