COMPAEATIYE MORPHOLOGY OF THE GALEODID.E. 4!07 



EXPLANATION OF THE PLATES. 

 Plate XXVII. 



Fig. 1. A specimen of Cleobis, dorsal aspect to sho\v the metamerism. 3, 4, 5, 6, cephalothoracic 

 segments. I-X abdominal segments. Immediately behind the cephalic lobes {d), a pair 

 of triangular selerites represents the remains of the tergum of the 3rd segment (3). The 

 tergum of the 4th segment (4), transformed into a pair of solid rods, which anteriorly 

 hold up the cephalic lobes, and posteriorly are continued in the lateral walls as strong 

 pillars, rising from the ventral skeletal framework (c/. PI. XXVIII. fig. 15, r). The terga of 

 5 and 6 differ in no important respect from those of the abdominal segments. Flexible 

 membranes form the sides of the body, a, specialized area of the cephalic lobes. 



2. Side view of the same, showing the flattened cephalic lobes characteristic of Cleobis. The 



eyes project from a slight forehead-like bend of the anterior edge of the cephalic lobes. 

 The rod-like formation of the tergum of the 4th segment supports the posterior edge 

 of the cephalic lobes. The sides of the body are covered with a flexible membrane 

 through which muscle- strands can be seen. The lateral eye is on the specialized area (a). 



3. Sketch of the cephalic lobes of Solpui/a paludicolla, Pocock, showing the strong suture and 



the projecting ocular tubercle. The tergum of the 3rd segment, only partly covered by the 

 paired cephalic lobes. The supporting rods (tergum of the 4th segment) nearly meet in 

 the middle line. 



4 . Part of the anterior dorsal surface of Galeodes caspius, Birula. 



5. Lateral view of the same region in Galeodes arabs, C. Koch, showing the cephalic lobes at an 



angle with the tergum of the 3rd segment, a large portion of which remains uncovered in 

 this genus. 

 € & 7. Dorsal and lateral views of the same region in Rhax termes. The tergum of the 3rd segment 

 reduced to a very narrow border behind the short, round cephalic lobes. 



8. A, B, C, D. Diagrams to show the possible origin of the cephalic lobes (cl) as lateral portions 

 of the 1st segment (1) shifted on to the dorsal surface {ds) above the labrum (L), owing to 

 the translocation of the 1st pair of appendages [ch) from a lateral to a preoral position. 

 The ocular tubercle is the remains of the old dorsal surface [ds] (cf. fig. 10). For the develop- 

 ment of the chelicerje, cf. PI. XXIX. fig. 1, a, b', c' . 



9 a. Partly diagrammatic section through Galeodes (traced with camera lucida), showing the 

 relative sizes and positions of the chelicerje {ch) and the pedipalps {pp). L, the labrum or 

 beak. 9 6. The same of Scorpio, showing the small size of the chelicerse (ch) as compared 

 with the pedipalps (pp). The cephalic IoIjcs have shrunk to a flat carapace on each side 

 beyond the chelicerse. L, labrum ; /j and L, spoon-like processes of the coxae of the 1st 

 and 2nd legs (appendages 3 and 4) ; ff, section through the gutter on /j. 9 c. The same of 

 Obisium. I, labium. For the sections through these beaks, cf. PI. XXVIII. figs. 3, 9, 10. 



10. Dorsal surface of Palceophorms nuncius, after Thorell and Lindstrum, showing the ocular 



tubercle as portion of original dorsal surface {ds), being grown over by the cephalic lobes 

 {cl). 



11. Part of a dissection from the side of Galeodes arabs, right cephalic lobe and right chclicera cut 



away. The cephalic lobe is seen to end posteriorly as a blind pocket, resting on the tergum 

 of the 3rd segment. The median suture («) is seen as a longitudinal ridge projecting 

 inwards. The inner side of the left chelicera is seen, showing the basal smooth area 



