273 



sensory buds are also very numerous on the lips of many Teleosts 

 that have no tentacles, though whether they are found on the lips of 

 all Teleosts, and on the lips of Elasmobranchs as well, I do not know, 

 not being able to refer to Merkel's well-known work on this subject. 

 If they are found on the lips of all fishes, and if they are centers of 

 osteoblastic proliferation, as seems extremely probable (No. 3, p. 429) 

 if Klaatsch's (No. 22) much contested conclusions be accepted, the 

 Teleostean maxillary bone may be primarily developed in relation to 

 them and not to the teeth it so relatively rarely bears. This would 

 seem to be also indicated by the relatively late date at which the 

 maxillary teeth appear in Amia. The maxillary bone is found in 12-mm 

 larvae, as are also the premaxillary and dermo - palatine bones with 

 their associated and well-developed teeth, but it is not until the fish 

 is about 40 mm long that the maxillary teeth begin to appear. They 

 then, and also when the fish is 50 mm long, lie at right angles to the 

 flat surface of the maxillary bone, along, or just beyond, its ventral 

 edge, the posterior ones having a nearly horizontal position, with their 

 points directed mesially. They are thus in no way opposed to, or 

 related in their development to, the dentary teeth, those teeth de- 

 veloping concomitantly with, and being directly opposed to, the large 

 dermopalatine ones. The late development of the maxillary teeth, re- 

 lative to their underlying and supporting bone, cannot here be ex- 

 plained, as it is in the higher vertebrates, by the assumption of an 

 "entwickelungsgeschichtliche Fälschung, hervorgerufen durch das längere 

 Eileben" (No. 35, p. 556). 



In Lepidosteus osseus there are three or four dermal bones that 

 are said by Parker (No. 31, p. 478) to have, to the adjoining parts 

 of the head, "all the relations of the free part" of the maxillary and 

 jugal bones of Teleosts. These bones are not toothed in Lepidosteus, 

 and as they are apparently separated from the underlying bones of 

 the skull by a deep crease, they thus probably lie in a maxillary fold 

 that occupies a position corresponding exactly to that of the hind end, 

 at least, of the maxillary fold of Amia. In front of these three or 

 four bones there is a long chain of dermal bones, all of which are 

 said to be both traversed by the preorbital part of the main infra- 

 orbital lateral canal of the fish, and to bear, on their ventral edges, 

 a single row of small sharp teeth. These bones are called by Parker 

 the maxillary chain, and they might be considered as typically re- 

 presenting that early condition of the maxillary bone, a series of tooth- 

 bearing plates, that Sagemehl believed in. It is, however, evident that 

 these bones of Lepidosteus cannot be the homologues of the maxillary 



Anat. Anz. XVin. Aufsätze. 18 



