BY H. H. SCOTT AND CLIVE K. LORD. 101 



this cartilage a chondro-cranial relic, or anything else of 

 a like nature, but the Rorquals show well develooed ethmo- 

 turbinals, and other whales also in part develon the 

 sense capsule?. Accordingly we are really dealing with 

 a suspension of ostosis, under pressure of racial evolu- 

 tionary needs. Retaining this thought in the mental 

 foreground, we set out to examine this cartilage in vari- 

 ous Dolphins' skulls, with the following results. 



1. We are impressed with the fact that the enormous 

 variation of a Dolphin's skull in the nasal regions, must 

 have first retarded the ostosis of a considerable area ; next, 

 the ossific processes acting upon the now changed, and 

 modified area, accelerated ostosis iti some parts, and re- 

 tarded it in others. As an illustration of accelerated and 

 extended o.ssific energy, we may cite the vomer in Dol- 

 phins' skulls. Its basic position insures an early ossifica- 

 tion of all its parts, which is suificiently complex, bv the 

 way, to rule out the term "azygous bone, " since it not 

 only extends enormously foi-wards, but posteriorly ex- 

 pands over the whole sphenoid element, and even reaches 

 the basi-occipital. Looking to other vertebrates, we find 

 that Tonkoft', in 1902, saw its paired origin indicated in 

 the bird, although frequently overlooked. In the croco- 

 dile it practicallv has three centres, two giving rise to the 

 palatine moieties, and a third to a central portion that 

 is embraced bv the ptervgfoids. Traces of this latter 

 appear in Dolphins' skulls, while to crown all we get the 

 additional extension backwards just cited. Sir W. 

 Flower was always careful to point out that so-called 

 "azvgous bones" were onlv those whose compound origin 

 was so remote as to be uneasy to trace, a fact our studies 

 have served to recall. 



3. As an instance of retarded ostosis, we may name 

 the ethmo-nasal regions of Dolphins' skulls. 



4. In verv voung Dolphins' skulls the whole of this 

 area, including the pre- frontal, and nasal regions, retains 

 the condition of a more or less semi-cartilaginous stat^e, 

 showing its recent evolutionary remoulding. The same 

 skulls, however, will have the vastly extended vomer, 

 completely, and perfectly ossified (including even its basi- 

 sphenoidal plate). 



5. The manner in which the bony elements at the 

 vertex of Dolphins' skulls blend, and inter-blend, accord- 

 ing to the various factors of genera, is extremely interest- 

 ing, as note. 



In Delphinus, the nasals early fuse with two lateral 

 strips of the ethmoid cartilage, and so extend down the 



