710 ANNEXE I 
that have been made by Axprews seem to show that the Sirenia have 
several characters that suggest an approximation to the Proboscidian 
type. The abdominal testes, zonary placentation, non deciduate placen- 
tation, Pectoral mammæ, bifid apex of the heart, usual absence of fora- 
men in lower end of humerus, Similarity in form of molar teeth etc. and 
the teeth being pushed forwards in advancing age (Summary by Lypek- 
KER in Knowledge). The recent investigations in the early tertiary Pro- 
boscidia seem to show a nearer approach of the Proboscidia to the Ce- 
tacea than many thought. The lower jaw of Tetrabelodon as figured by 
WoopwaRp in Knowledge is much more like that of WMesoplodon Hectori 
than is the jaw of other Elephants. But the great capacity of the skull 
cavity seems to point also to an alliance of earlier types, although one 
can never expect to prove an absolute affinity. The great size of the brain 
in the Elephants and in the Whales also is not without significance. 
The outline drawings made from Mesoplodon and Orca are in Irish 
Natur. 1900. 
The photographs were made by Dr. Wurre of the Royal College of Sur- 
geons Museum, Dublin, Miss M. K. Axprews of Belfast, Mr. Rogixsox of 
Oxford by permission of Prof. Wezpox and Mr. Sloan Miss of Galway. 
Prof. Ray Laxkesrer of London, formerly of Oxford who is quoted by 
Tuexer, has helped me to get a photograph of Ziphius cavirostrus, which 
may make this paper more complete. 
I am indebted to the writings of the gentlemen named in this paper. 
Prof. Turxer says! : In Mesoplodon Layardi the sphenoïd takes but a 
very small part in the formation of the temporal fossa. The parietal forms 
the greater part of its floor and in the young skull could be foll owed as a 
distinct bone situated between the supra occipital and the frontal to the 
vertex, where it was united by synostosis to its fellow. In the adult, though 
the outline of the parietal in the temporal fossa could be readily seen, no 
part could be traced beyond the fossa to the vertex, for it was overlapped by 
the growth of the supra occipital, so that only the thin edge of the fron- 
tal bone appeared in the interval between the supra occipital and the 
superior-maxillary. The vertex part of the frontal articulated in A. 
Layardi as in M. Sowerby with the maxillæ, premaxillæ and nasals an- 
teriorly. The frontal formed the roof of the orbit and had a large post 
frontal and a small prefrontal process. The malar consisted anteriorly 
of a flattened piece which articulated with the superior maxillæ and la- 
chrymal, a posterior zygomatic bar that reached beneath the orbit and 
articulated with the zygomatic part of the temporal. The lachrymal ar- 
ticulated with the preorbital part of frontal, the superior maxillary and 
the malar in M. Luyardi and M. Sowerby. 
! Challenger Report, p. 9. 
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