THE CETACEA, OR WHALES. 247 



collections and observations on the shores of the 

 Arctic Ocean. Holboll furnished the museum of 

 Copenhagen with excellent material in the way of 

 skeletons, together with the softer portions of the 

 body, also whole animals of various ages, with 

 detailed accounts of the biological observations he 

 had made. All this information Eschricht 1 made 

 use of in a classic work, where he traces the trans- 

 formation of the skull of the foetus (only some few 

 feet in length altogether) to that of the full-grown 

 giant, that framework which strikes the on-looker 

 at first as perplexingly strange. He cleared up the 

 relation between the bearded and the toothed Whales 

 by following up Geoffrey's discovery more minutely, 

 i.e. by showing that the foetus of the Bearded or 

 Whalebone w r hale possesses a number of small teeth, 

 which never cut through the gums, and subsequently 

 become completely re-absorbed, when the huge 

 sieve-like apparatus on the mucous membrane of 

 the gum appears. The rudimentary teeth of the 

 Whalebone whales, which never come into use, are 



1 Eschricht, Zoologisch-anatomiscli-pliysiologisc'he Unterstich- 

 ungen ilber die nordischen Walthiere (Leipzig, 1849), of which 

 work there is an English translation ; also Brandt, ' Untersuch- 

 ungen iiber die fossilen und sub-fossilen Cetaceen Europas,' 

 Mem. Acad. Petersb., 1873 ; Van Beneden et Gervais, Osteographie 

 dcs Cetacts. Paris, 1868-80. 



