E. LÖNNBERG, ON THE RHAMPHOTHECA OF BIRDS. 489 



lateral shields. This might be taken to be a nasale and 

 homologous with a piece which is found in a higher degree 

 of development in Tubinares (conf. below). The lower jaw 

 is in this penguin covered by an infralabial shield on either 

 side which both join together in a median sntnre at the 

 distal end. The mentale has wholly disappeared in this spe- 

 cies, but in another larger, Spheniseus magellanicus, there 

 seeins to be a rndiment left at the distal end of the lower 

 jaw as the median sutnre is not continued so far forward. 

 In the same there seems also to be a narrow and small first 

 labial between the rostrale and the large labial shield. This 

 deserves the more attention as a similar piece is still better 

 developed in other birds (conf. below). A richer material 

 of Impennes will undonbtedly help to confirm this theory 

 but I have to leave this for the present. It mnst however 

 be remarked that in none of the species examined by me 

 was found any piece that needed to be explained as a sub- 

 mandibular. This piece appears therefore to be missing in 

 the bill of penguins. 



In the Tubinares the different pieces of the rhamphoteca 

 are very distinct. In species of Diomedea the homologon to 

 rostrale forms a powerful hook which is more or less plainly 

 distinct from the »culminicorn» which corresponds to an inter- 

 nasale (resp. frontonasale). Below the latter, extending from 

 the nasal region and to the rostral hook, is a long and narrow 

 shield, which reaches the (pre-)maxillary margin just behind 

 the rostral hook and forms there a more or less tooth-like 

 projection. I take this to be a first labial which with 

 the growth and increasing length of the bill has become 

 prolonged in such a manner. The (pre-)maxillary margin 

 behind this first labial is formed by a more strongly deve- 

 loped shield, the »latericorn», corresponding to a second labial 

 (or perhaps several fused ones). The curved semitubular 

 shield surrounding the nostril of either side corresponds of 

 conrse to a nasale and has also such a situation between the 

 labial and internasal shields. On the lower jaw there is a 

 longitudinal, but quite well developed mentale intercalated 

 between the nfralabials of both sides. On either side is 

 found a massive first infralabial, which, when the jaws are 

 shut, is in contact with the rostral hook and includes the 

 toothlike projection of the first labial, but its own margins 



