Small Foetuses ol' Lagenorhynchus aeutus. Gray, 



witli the incipient characters of Odontoceti. 



Fig. 1. Lagenorhynchus aeutus, Gray, 26 niiliim. long tætus, seen from the right side: natural size. A distinct con- 

 striction of the neck is visible, a short facial region and rounded cranium with the nasal aperture high up; fore- 

 linihs distinct; rudiments of hind-limbs not visible to tlie naked eye: tail conical and relatively large. 

 2. The same foetus seen from the left side: natural size. 

 „ 3. Same foetus, seen from the ventral surface: natural size. Distance between nasal aperture and mouth cleft 

 already considerable. 



4. Same fætus. seen ii-om back: natural size. Slight depression in the back of the neck, indicating the 4th ventricle. 



5. Same fcetus, magnified 3 times, seen from the right side. The pronounced foetal flexures are noticeable, the con- 

 striction of the neck, a ventral and a lateral side-furrow, a prominence to the side of the membrum genitale 

 (rudiments of hind-limbs), and a well-developed, conical tail. 



6. Same fætus, magnified 3 times, seen from the left side. 



7. Same foetus, magnified 3 times, seen from the ventral surface. 



H. Lagenorhynchus acutus, Grray, 30 millim. long fu'tus. seen from the right side: natural size. 

 9. Lagenorhynchus acutus, Gray, 45 millim. long fætus. seen from the left side: natural size. The Cetacean 

 characters are here more conspicuous. Pigmentation at the back of the head begins to appear. 



10. Same fcrtus. twice the natural size. Left side. 



11. Same f(t'tus. twice the natural size. Ventral surface. 



.. 12. Lagenorhynchus acutus. Gray, 94 millim. long fætus; natural size, right side. Pigmentation of the skin in 

 the region of the back of the neck and on the back, is already distinct, 

 l.'i. Same fætus. left side, natural size. 

 14. Same fætus, ventral surface, natural size. 



Kigs. 1 — 7 and figs. 12 — 14 are drawn by H. Budier. jun. in Bergen; figs. 8 — 11 are drawn by Olaf Bergh, medical 

 student. ( 'hristiania. 



