172 MR. G. C. BOURNE ON THE 



least one member of the group, and I have no doubt that a closer 

 investigation will show that it is of general occurrence. 



The character of the trachea, the curved alimentary tract, the 

 numerous chitiuous pieces composing each segment, and the 

 presence of a special sense-organ on tlie head, mark off the 

 family Grlomeridge, to which Splicer otherium belongs, very sharply 

 from the other families of the Diplopoda. 



In conclusion I must express my thanks to Professor Moseley, 

 who kindly gave me the specimens with which. I have worked, 

 and assisted me in many other ways. 



I am also much indebted to my friend Mr. "W". Baldwin 

 Spencer, who has kindly undertaken to see my work through 

 the press during my absence from England. 



EXPLANATION OF THE PLATES. 

 Plate XXVII. 

 Fig. L Lateral view of a large specimen of SphcBrotherium obtusum, nat. size. 

 2. 8. obtusum. Left first accessory appendage of the male, viewed from 

 behind. 1, proximal joint; 2, middle joint; 3, distal joint. ]). Claw- 

 like process of middle joint at the base of which the distal joint is 

 articulated, thus forming a chela, a. Hood-like process on distal 

 joint, a'. Parallel ridges on a which work againt the process p, thus 

 forming a stridulating organ. 

 3: Second pair of accessory appendages of 8. ohtusiom, ^ . 1, 2, 3. The 

 three joints of the appendage. /. The /orcipw/es copulatrices (Fabre) 

 formed by the middle and distal joints, a. Stridulating organ. 

 b. Penes. 



4. Stridulating organ on the second accessory appendage of Sphcsrotherium, 



much magnified. 



5. Accessory appendages of 8. retusum, (^, viewed from behind. 1, 2, 3. 



Joints of second accessory appendage. /. Forcipules copulatrices. 



a. Stridulating organ. 



6. The same viewed from in front. I. & II. The first and second 



accessory appendages. 1, 2, 3. Joints of second appendage. /. For- 

 cipules cojndatrices. a. Stridulating organ, p. Penes. 



7. The last shield-shaped tergite of 8. obtusum. a. External surface. 



b. Concave internal surface, c. Thickened and produced inferior 

 margin, d. The rasp-like stridulating cushion developed on the 

 internal surface and against which the stridulating organ (fig. 4, and 

 a, figs. 3, 6, 6) works. 



8. Single tracheal sac of 8. obtusuon, viewed from the inner side, and 



attached to its tracheal plate, a. Tracheal sac. a^. Angle of the sac 

 which is attached to the tracheal plate (c). or', a?. The two angles of 

 the sac from which spring the tracheal tubes {d, d). b. Stigma, 

 opening into the tracheal sac at the angle a}. 



