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



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

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

 turbinals, and other whales also in part develoD 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 enormoua 

 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 in some parts, and rei- 

 tarded it in others. As an illustration of accelerated and 

 extended ossific energy, we may cite the vomer in Dol- 

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

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

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

 ■only extends enormously forwards, 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 practioally has three centres, two giving rise to the 

 palatine moieties, and a third to a central portion that 

 is embraced bv the pterygoids. Traces of this latter 

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

 additional extension backwards just cited. Sir W. 

 I'lower was always careful to point out that so-called 

 "azygous bones" were only 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 very young Dolphins' skulls the whole of this 

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

 the condition of a more or less semi-cartilaginous state, 

 showing its recent evolutionary remoulding. The same 

 skulls, however, will have the vastly extended vom-er, 

 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 



