OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 55 



16. Gentoo Penguin Embryo, 26 Days. 



The embryo was fully formed ; the eyes looked large and prominent ; the beak was soft. 

 The head was covered with short black down ; the rest of the body was practically naked. 

 Along the middle line of the abdomen, from the umbilicus to the root of the neck, was a 

 well-marked groove. 



17. Gentoo Penguin Embryo, 27 Days. (Fig. 25.) 



The limbs of the embryo appeared fully formed. The feet were flexed over the front 

 of the abdomen, plantar surface outwards. The upper limbs lay close to the side and 

 over the abdomen under cover of the feet. The neck was flexed so that the beak lay along 

 the right side of the abdomen immediately internal to the right superior extremity. 

 Down was plentifully present on the head and back, shading from almost black over the 

 head to a light slate grey over the sacral region. The down on the abdomen and anterior 

 aspect of the thorax was sparse and light in colour. The middle line of the body in 

 front was marked by a very evident ridge in the lower part, flanked on either side by a 

 groove. These grooves coalesced in the upper part of the abdomen and were continued 

 over the thorax as a median depression. This could be traced as high as the root of the 

 neck, where it was lost. 



18. Gentoo Penguin Embryo, 28 Days. 



The embryo appeared fully formed and was in a fully flexed position, so that the 

 under surface of the mandible was pressed firmly against the thorax and abdomen ; the 

 beak lay in a groove formed by the right fore limb and left hind limb. The head was 

 covered with a dark grey, almost black, down ; the back with slate coloured, the abdomen 

 with white. The back of the head had been flattened by pressure. 



Duck Embryos, 19-28 Days. 



The advance was purely one of body bulk. The amount and directions of growth 

 are shown by the measurements of the specimens. (See Table I.) 



19. Gentoo Penguin Embryo, 30 Days. (The specimen in fig. 25 closely 

 resembled this older specimen, but was rather smaller.) 



The embryo appeared fully formed and was in a fully flexed position, so that the under 

 surface of the left side of the head was pressed against the thorax, the beak lying to the 

 right side of the abdomen between the right fore limb and the foot of the left hind limb 

 anteriorly and the right hind limb posteriorly. The head and back were covered with 

 slate-coloured down, the belly with white down. In the flexed position the greatest 

 length was 571 cms., the greatest breadth 3'05 cms. In the extended position the 

 length from the crown of the head to the tip of the tail was 8 '41 cms. When measured 

 separately the head was 2'55 cms. in length, the neck T85 cms. ; the body and tail 



(ROY. soc. EDIN. TRAXS., VOL XLVII., 241.) 



