The small Embryos of Phocæna communis, Less. 



Fig. 1. A 7 millim. long embryo, natural size. Fore and hind extremities visible. 



„ 2. A 17 millim. long embryo, natural size, seen from left side. 



„ 3. Same embryo, natural size, seen from ventral surface. The eyes are visible, and the double sigmoid nasal aperture, 

 lying like a transverse fissure. 



„ 4. An 18 millim. long fætus, seen from the left side. 



,, 5. The same fætus, seen from the ventral surface. The nasal aperture is here seen on a level with the eyes, and 

 below is the broad mouth cleft. 



„ 6. The 7 millim. long embryo, magnified 4 times, seen from the right side. The small fore-extremities and the very 

 small hind-extremities are noticeable, and the very long tail. The eye (o) is indistinct, while the maxillary process (mx), 

 lower jaw, 1st visceral groove and 2nd visceral arch are distinct. Behind this last is a rounded groove, fovea 

 or sinus præcervicalis. m = mesencephalon; /. rh = fovea rhomboidalis; n = neck-flexure; fl = fore-limb; 

 h. e ^ hind limb; t. y = tuberculum genitale; u = umbilicus; ns = the forebrain. 



,. 7. The same embryo, seen from the left side. Magnified 4 times. 



„ 8. The same embryo, seen from the back, where a i-aphé is visible in the middle, and somites to the sides. 



,. 9. The back of the neck of the same embryo with a riiomboidal groove, indicating fovea rhomboidalis. 



„ 10. Side view of the head of the same embryo magnified 8 times, n = flexure of the back of the neck; m = flexure of 

 the crown of the head with mesencephalon; o = eye; ns = olfactory pits; mx = maxillary process; mh = 

 lower jaw; hy = 2nd visceral arch: fp = The fovea præcervicalis, with the third visceral arch. 



,. 11. Head of the same embryo, seen from the ventral surface, — the facial region, m = mid-brain; km = cerebral iiemis- 

 pheres; o = eye; ny = olfactory pits on the fronto-nasal process; I) = boundary furrow between the maxillary 

 process and fronto-nasal process; mx = maxillary process; mh = lower jaw. 



,. 12. Hind part of the same embryo, magnified 16 times, and showing rudiments of hind-extremities, u = umbilical cord; 

 /•. u. = vesicula umbilicalis; sm = proto-vertebræ; h- I. = hind-extremity; ty = tuberculum genitale. 



,, 1.3. The 17 milHm. long embryo, magnified 4 times, seen from the right side. )t. = flexure of the back of the neck : 

 f.rli = fovea rhomboidalis; »» = flexure of the crown of the head with the mesencephalon; the = thal.inience- 

 phalon (supposed); he = cerebral hemispheres; ff' = frontal furrow; ny = external nasal aperture; nc = 

 external ear opening; (( = umbilical cord; he = hind extremity in a retrogressive state; y = genital mcniber. 



,. 14. Front view of the same embryo, magnified 4 times. 



,. 1 .5. Back view of the same embryo, magnified 4 times. ///( = fovea rhomboidalis with marked lateral expansion ; 

 /'(' = intumescentia cervicalis; il = indication ot intumescentia lumbalis. 

 1 li. Same embryo seen from the left side, magnified 4 times. 



17. The 18 nnllim. long fætus; front view, magnified 4 times. 



18. Same fietus seen from the left side; magnified 4 times, 

 lit. Front view of the head of the same fætus. 



,. 20. Hinder part of the same fætus, magnified 6 times, he = remains of external rudimentary hind-extremity; // ^ 



genital member. 

 ,, 21. Right ear-opening of the same tætus, drawn by Prof G. Guldberg with an Abbe's camera luc. obj. aa oc :i. 



Figs. 1 — 20 from original drawings by Olaf Bergh, medical student. 



