ANATOMY AND GENERIC CHARACTERS OF SCORPIONS. 383 



of the mouth. For the muscles referred to by numbers, see the list on 

 p. 359. 

 Fig. 15. View from below of the pericardium, arteries, pericardio-ventral (veno-peri- 

 cardiac) muscles, and dorso-ventral muscles of Androctonus occitanus. 

 Magnified two diameters, and drawn from an actual dissection. 



pp l -pp*, the series of pericardio-ventral muscles running from the peri- 

 cardium to the wall of the great ventral vein or sinus of the same side ; 

 ar x -mfi, the lateral arteries of the mesosoma ; ar 7 , the lateral artery of the 

 first metasomatic segment ; dv x -dv Q , the six dorso-ventral muscles of the 

 mesosoma ; dif, the dorso-ventral muscle of the first metasomatic segment. 



PLATE LXXXI. 



Figs. 1 and 2. Transverse sections of the mesosoma of Scorpio italicus, to show the 

 venous blood-spaces and the pericardio-ventral muscles. 



alax, axial portion of the alimentary canal ; ale, glandular caeca of the 

 alimentary canal ; cc, coagulum within the heart ; cv, valve and aperture of 

 the heart-wall ; cog, coagulum in the pericardial blood-space ; cpb, fibrous 

 bands from heart-wall to pericardium (ventral) ; cpu, similar dorsal bands ; 

 cw, heart-wall ; dvsl, deep latero-dorsal vein or blood-sinus ; svsl, superficial 

 latcro-dorsal vein (same as marked svsl 1 ' 6 in PI. LXXX. fig. 1); gc, 

 genital follicles (testis) ; lb, lamellae of lung-book ; Ivm, longitudinal ventral 

 muscle ; Ig, ventral insertion of dorso-ventral muscle ; Idm, dorsal longi- 

 tudinal musculature ; n, nerve-cord ; pvs, pericardial blood-space ; ppm (in 

 fig. 2), the pericardio-ventral or pericardio-pulmonary or veno-pericardiac 

 muscles passing from the pericardium to the roof of the circumpulmonary 

 blood-sac ; ps, the circumpulmonary blood-sac ; spa, supramedullary artery 

 of Newport. 



Figs. 3 and 4. Transverse sections of the lamellae of the lung-books of Androctonus 

 funestus, showing the blood-spaces, B, containing blood-corpuscles, be, and 

 traversed by short cell-columns, cc (as in Limulus), and the air-spaces, A, on 

 the lining of which the cuticle is roughened (ornate). 



In fig. 3 the drawing is inverted since the points y y are the free ends of 

 lamellae, which stand upwards into the blood-space, the spaces between these 

 air-holding lamellae being open to the blood-current. 



In fig. 4 the section passes through a region where the ends of the air- 

 holding lamellae are fused to the wall of the circumpulmonary blood-sinus 

 and to one another by the tissue x. 



Fig. 5. Reticular ornament from the air-bathed surface of a lung-lamella of Androctonus 

 funestus, near the centre of the lamella. 

 vol. xi. — pakt x. No. 10. — May, 1885. 3 l 



