54 DR D. WATERSTON AND DR A. CAMPBELL GEDDES ON EMBRYO PENGUINS 



11. Gentoo Penguin Embryo, 21 Days. 



The embryo was completely flexed ; the limbs were completely formed. The 

 integument over the abdomen was incomplete; a triangular area 1'23 cms. in length, 

 07 cm. in breadth, extended forward in front of the umbilicus and was continued over 

 the front of the thorax as a well-marked groove from which on either side extended 

 twelve transverse grooves. 



12. Gentoo Penguin Embryo, 22 Days. (Fig. 17.) 



The limbs of the embryo were complete ; the integument over the abdominal 

 regions was incomplete. An area 1 '04 cms. in length and "09 cm. in breadth at the 

 umbilicus, gradually tapering to a point, was undeveloped. The head and body were 

 entirely naked. The eye prominences were very marked ; the skull and beak were soft 

 and pliable. There were five transverse grooves on the abdomen. Flexion was 

 incomplete. 



13. Gentoo Penguin Embryo, 23 Days. 



The embryo was not quite fully developed, the integument being incomplete. On 

 the anterior abdominal region anterior to the umbilicus a very acute isosceles 

 triangle persisted uncovered, the sides of which measured T19 cms., the base '12 cm. 

 The eye prominences were very marked, the skull and beak were soft and pliable. A 

 few short pieces of dark down had developed on the head ; the rest of the body was 

 absolutely naked. There were no transverse grooves on the abdomen ; flexion was 

 incomplete. 



14. Gentoo Penguin Embryo, 24 Days. (Fig. 23.) 



The embryo was fully developed. The prominence of the eye-balls was well marked 

 and the eye-slit was open, 1 8 cms. long ; its width at its broadest part when stretched 

 was '08 cm. The head was covered with dark down, and on the back and body there 

 was a sparse covering of light-coloured down considerably more than on the 25-days' 

 embryo. The middle line of the front of the abdomen showed a deep groove from which 

 extended across the abdomen, on either side, six well-marked transverse grooves. The 

 feet and tail had now assumed the adult relations, and formed the peculiar flat base 

 which is characteristic of the adult bird and permits of its adopting the quasi-erect 

 attitude habitual to it. 



15. Gentoo Penguin Embryo, 25 Days. (Fig. 24.) 



The embryo was fully formed. The prominence of the eye-balls was well marked. 

 The eye-slit was small, the beak was soft, and the head was sparsely covered with short 

 black down on the back. The body was fully flexed ; the spine formed a semicircle from 

 tail to head. There was a well-marked median groove on the front of the abdomen 

 and thorax, from which extended transversely on either side eight well-marked grooves. 



(ROY. soc. EDIN. TRANS., VOL. XLVII., 240.) 



