( 19 ) 



Fig. 6. Prsesternnm of another specimen of Flatanista showing variety in the 

 shape of the bone. 

 „ 7. Another variety in the figure of the first sternal piece of the Gangetic 

 Dolphin and belonging to a young animal. 



PLATE XL. 



Tabular view of the separated cranial bones of a mature foetus of Flatanista 

 gangetica, all drawn of natural size. 

 Pig. 1. The frontal bone looked at from behind and within, ^. e., its cerebral 



surface : op., minute optic foramen of left side ; fe., the back of the 



exterior frontal expansion of the bone ; and vo,^ projecting vomerine 



spine. 

 55 2. Supra-occipital, inside view showing {c.) median crest with lateral cerebral 



concavities (whereon the latter is placed) and below the cerebellar fossa 



with {cl.) cleft or fissure reaching the foramen magnum. 

 55 3. Posterior external surf ace of the right ex-occipital: c, condyle; /., jugular 



space. 

 55 4. An inside view of the left ex-occipital bone, {j\ ) being the jugular vacuity, 



the lateral sinus lying alongside. 

 55 5. The inner surface of the basi-occipital5 {fm,) resting at the edge of the 



foramen magnum. 

 55 6. Outer surface of the right parietal bone5 {sq,) being the roughened surface 



of the squamosal suture. 

 5, 7. Inner cerebral aspect of the left parietal ; the vascular groove {g,) of the 



arteria meningea media hem^WQ^jn.n;!^\QdihQ\ow. 

 „ 8. A view from below of the right temporal, or squamo-tympanic bones, {z.) 



being the zygomatic process and {spli.) the sphenoidal process. 

 55 9. Upper surface of the same bone of the left side : sq. roughened squamous 



sutural surface ; ty., tympanic ; pe., periotic ; sph.^ sphenoidal sutural 



surface ; z., zygoma. 

 „ 10. Interior aspect of the right tympanic bulla, i.e., that applied to the periotic. 

 „ 11. The basisphenoid, its upper cerebral surface. 



„ 12. The palatal ; {n.) surface of bone forming the wall of the narial passage. 

 „ 13. Internal surface of left pterygoid : n., smooth surface forming wall of narial 



passage ; pn., osseous limit posteriorly of narial passage ; sms., spheno- 

 maxillary sinus ; p., palatine surface ; hss., basisphenoid suture; op., orbital 



process ; bss., basisphenoidal surface. 

 5 5 14d. night pterygoid, its external surface \ p., palatine surface ; mxp., maxillo- 



palatine process; sts., spheno-temporal surface; op., orbital process ;^^., 



bony limit posterior nares. 



