( 21 ) 



Pig. 15. Upper surface of the two last dorsal and the first lumbar vertebra of Fla, 

 tanista gangetica ; reduced from nature: X and XI, segments of 

 the tenth and eleventh ribs ; t., transverse process of the first lumbar 

 vertebra. 

 5, 16. Outlines in a reduced scale of from I to X of the ten foremost ribs from 

 the right side of P. gangetica. 



PLATE XLII. 



The characteristic parts of the skeleton of the Irawady Dolphin Orcella 

 fluminalis, Anderson. Figures all considerably reduced from their natural dimen- 

 sions — 

 Fig. 1. The cranium in side view, | natural size. 



„ 2. The superior aspect of the same skull, ^ natural size. 



„ 3. The lower base of the same skull, ^ natural size. 



„ 4d. night moiety of the hyoid arch, ^ natural size : bh., basihyal ; th., thy- 

 rohyal ; ch., ceratohyal ; sh., stylohyal. 



„ 5. Fifth cervical vertebra, J natural size. 



,, 6. First dorsal vertebra, „ „ 



„ 7. Seventh dorsal vertebra, „ „ 



„ 8. First lumbar vertebra, „ „ 



„ 9. The forearm and manus : h., humerus ; r., radius ; u., ulna, ^ natural 

 size. 



„ 10. The thirteen ribs seen from the outside, |rd natural size. 



„ 11. The right pelvic bone, seen from in front, f rd natural size. 



PLATE XLIII. 



A comparison of some of the bones of Orcella fluminalis and of O. hre- 

 virostris — 



Fig. 1 Left scapula of 0. fluminalis, Anderson; its outer surface, ^ natural size. 

 „ 2. View of glenoid cavity of the same bone, \ natural size. 



3. Atlas and axis of O. fluminalis, seen from in front, -J natural size. 



4. Plight tympanic bone, &c., of 0. fluminalis ; its interior face and of natural 



size. Natural size. 

 „ 5. Sternum of O. fluminalis, \n^iuT2l^\7.Q. 



6. Left scapula of Orcella hremrostris ; its outer surface, J natural size. 



7. Glenoid concavity of same scapula, \ natural size. 



8. Atlas and axis of 0. hrevirostris, seen from in front ^ natural size. 



9. Pio'ht tympanic bulla of Orcella hrevirostris, the interior face of natural 



size. Natural size. 

 10. Sternum of 0. hremrostris, its inner aspect, \ natural size. 



