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'Fig. 15. The right malar bone, outer surface : o. p., orbital process. 

 „ 16. The inner surface of the same bone. 



17. The left maxillary, premaxillary and nasal bone in opposition and seen 



from the outside. 



18. The aspect of the same bones, also well showing the very characteristic 



overhanging maxillary, &c. The same lettering applies to this and fig. 17 : 

 c, crest ; n., nasal bone ; pmx., premaxillary ; mx., superior maxillary 

 bone. 

 „ 19. The left mandible, its exterior surface ; c, condyle ; a., angle ; co., coronoid 

 process ; /., pointing to two foramina. 

 Left moiety, seen from below, of the hyoid arch : bh., basihyal ; th., thyrohyal, 

 sh., stylohyal ; ch., ceratohyal. The letters point to the bony elements, 

 all the other pieces being cartilaginous. 



20 



PLATE XLI. 



Kg. 1. A cast of the cochlea, nerve tracts, and semicircular canals of Flatanista 



gangetica. Their natural size. 

 „ 2. The opposite side of the same preparation. 

 „ 3. Drawing of a cast of the semicircular canals of Flatanista, enlarged three 



diameters. 

 ,, 4. A cast of the cochlea, nerve tracts, and semicircular canals of Orcella 



hrevirostris. Their natural size. 

 „ 5. The opposite side of the same preparation. 

 „ 6. Sketch of the semicircular canals of Orcella hrevirostris. Enlarged three 



times natural size from the preceding specimen. 

 „ 7. A cast of the cochlea, nerve tracts, and semicircular canals of the genus 



GloMocephalus. Natural size. 

 „ 8. The opposite side of the same preparation. 

 „ 9. Its semicircular canals enlarged three times natural size. 

 „ 10. View cast of the cochlea, nerve tracts, and semicircular canals of Monodon 



monoceros. Of natural size. 

 „ 11. The opposite side of the preceding preparation of the narwhal. 

 „ 12. Semicircular canals of Monodon, enlarged three diameters. 

 „ 13. Left scapula of the Gangetic Dolphin Tlatanista gangetica ; its outer 



surface: g., glenoid concavity; a., acromion process; c., rudimentary 



coracoid process. 

 „ 14. Dorsal aspect of the bones of the left forearm and manus of Flatanista ; 



reduced. The lettering applies as follows : h., humerus ; r., radius ; u., 



ulna ; tm., trapezium ; rd., radiale or os scaphoid ; o. ^., os intermedium or 



lunare; td., trapezoid; mg., os magnum; c,u., cuneiform and unciform; 



m, m, m, m., the metacarpals ; I, II, III, IV, V, digits. 



