PLATE XIII. 



Fig. 51.— Cross section of a cirrus of the superior labial group of a male. C. L. ■ 20. 



A, artery. 



( !M, circular muscle layer. 



E, thickened epithelium of the inner (suctorial) surface of the annular ridge. 



LM, radially arranged longitudinal muscles. 



LM', outer layer of longitudinal muscles. 



N, nerve. 



().\l, oblique muscle layer. 



KM. radiating transverse muscle fibres inside the projecting portion of the annular ridge. 



TM, transverse muscle fibres surrounding the nerve and radiating outward between the longitudinal 



Y-, vein. 

 Fig. 52.- Longitudinal section of the tip of the first cirrus of the spadix. C. L. • 11. 



N. ner\ e. 



TM, alternating layers of transverse muscle fibres. 



V. vascular corium of the tip of the cirrus. 

 Fig. 53.— Cross section of the first cirrus of the spadix. ('. I.. ■ 7. 



A, artery. 



X, nerve. 



V, V, veins. 

 Fig. 54. — Cross section of the fourth cirrus of the spadix. C. L. • 14. 

 Fig. 55. — Longitudinal section of a gland of the second cirrus of the spadix. ('. L. ;■' 60. 



K. epithelium of the dorsal surface of the cirrus. 



< I, secretory epithelium. 



L, lumen of gland. 



X, neck of gland. 



