30 P. G. HEATHCOTE. 



numerous in the male, but this may possibly be due to 

 individual differences. I have not had a sufficient quantity 

 of males to make certain. 



The Malpighian Tubes. 



Bode succeeded in dissecting out the Malpighian tubes, but 

 their minute structure has never been described, and as they 

 show a variation from the ordinary form of these organs which 

 is not found in any other Myriapod, it is worth while to give a 

 short account of them. 



Each tube — there are a pair of them — leaves the junction of 

 the rectum and mid-gut as a stout tube with a definite lumen. 

 The lumen is surrounded by a ring of denser tissue which 

 has a faintly striated appearance. Each tube passes backwards 

 along the rectum to the terminal dilation of the latter where it 

 becomes greatly thickened, and is doubled upon itself so as to 

 form a great spherical knot, the greater part of which lies in 

 the semicircular chitinous elevations which are placed at 

 either side of the anus. From this coil each tube passes oft 

 greatly reduced in size so as to have the form of a thin tube 

 (figs. 8, 9, 6, r. malp. t.) like any other Malpighian tube. 

 These two thin returning portions pass forward and end 

 blindly about the middle of the body. From the anterior-end 

 of the rectum, where the Malpighian tubes originate, the whole 

 of these structures, together with the rectum, is enveloped in 

 a membrane (figs G, 8, 9) which passes backwards and becomes 

 fused with the mass of cells forming the hypodermis. This 

 membrane is perfectly definite on the external surface of the 

 Malpighian tubes, but I have been quite unable to find any 

 trace of it between the tubes and the rectum. I am con- 

 vinced that it envelopes the tubes and the rectum together. 

 Where the small returning portions of the Malpighian tubes 

 pass beyond the origin of the tubes and the enveloping mem- 

 brane, at the anterior end of the rectum, they pierce the 

 membrane, and passing forward lie close to the mid-gut just 

 like other Malpighian tubes. 



The salivary glands, which are long and tubular, open on 



