8o SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 72 



sumably fitted. True refers it provisionally to the family Iniidce 

 {=Platanistid(e), perhaps rightly; there are other possibilities. 



^^ (Pp. 26 and 31.) True (A Review of the Family Delphinidse; 

 Bull. U. S. Nat. Mus., No. 36, 1889, p. 10) believes he has observed a 

 peculiarity in the relationships of the pterygoid that should distinguish 

 Dclphinapterus and Monodon from all other Delphinids and recall 

 the Platanistids : " that in the narwhal and white whale the pterygoid 

 bones, instead of merely forming the walls of the posterior nares, 

 extend backward in the form of broad plates across the optic canal 

 and articulate with the squamosals." But the case is different. We 

 have to do with the bones which lie in the outer wall of the air-sac 

 behind the palate. As may be seen in young or youngish skulls of 

 Delphinapterus and Monodon, the pterygoid shares in the formation 

 of the outer wall of the air-sac at the front only, in contrast with the 

 condition in Pontistes, Pontoporia and Platanista in which it, recall- 

 ing the Balsenids and Physeterids, forms most of the outer wall (in 

 I Ilia the outer wall appears to be mostly membranaceous). As in 

 other Delphinids the palatine, frontal, ala magna, and squamosal all 

 share in bounding the outer side of the air-sac, each contributing its 

 section (special ossifications may also be present). In the Delphinids 

 under discussion the outer side of the air-sac is merely ossified more 

 extensively than elsewhere, a difi^erence, however, which is one of 

 degree only. 



" (P- 35-) As reasons for believing that Ncomeris and Phocana 

 among recent Odontoceti are the ones which stand nearest to Zcu- 

 glodon and Squalodon Abel (Dauphins Longirostres, 1901, p. 36) 

 mentions the following : ( i ) that they still have traces of " I'ancienne 

 dentition heterodonte," (2) that teeth are still found (or more cor- 

 rectly may be found) in the intermaxillary, and that the intermaxillary 

 extends further forward than the maxillary, (3) that they still have 

 traces of " I'armure dermique," (4) that the nostrils are not pushed 

 very far backward, and that therefore the parietal still extends up 

 back of the frontal. Against this view there are the following objec- 

 tions : ( I ) The form of the teeth in the two recent genera is not 

 primitive ; fan-like broadened crown and single root is not the form 

 of tooth that is found in the more primitive cetaceans of any kind. 

 Conical crown and a trace of double root, in most of the teeth, is the 

 transitional form between the tooth structure of the more primitive 

 and the less primitive cetaceans. Even the anterior teeth in the jaws 

 of Phoccsna may have fan-shaped crowns, where in the most primitive 

 whales they are unicuspid and conical. (2) Teeth in the inter- 



