204 PROFESSOE FLOWEE ON THE EECEXT ZIPHIOID WHALES. 



opportunities will become more and more frequent as the attention of naturalists in 

 various parts of the world is directed to the importance of never omitting any chance of 

 observing and, if possible, securing the remains of every specimen of the group that 

 may come within his reach. 



The Ziphioid ' Cetaceans belong to the great primary division or suborder of the 

 Odontocetes, or Toothed Whales. The following are their principal common charac- 

 teristics, as far as they can be defined in the absence of sufficient knowledge of the 

 structural characters of several forms : — 



1. No functional teeth in the upper jaw. 



2. Teeth of mandible quite rudimentary and concealed in the gum, with the excep- 

 tion of one, or occasionally two, pairs, which may be largely developed, and project like 

 tusks from the mouth, especially in the male sex. 



3. Bones of the cranium raised so as to form an elevated prominence or crest behind 

 the nares. 



4. Rostrum long and narrow. 



5. Pterygoid bones very large and solid, produced backwards, meeting in the middle 

 line, and not involuted but simply hollowed on the outer surface. 



6. A distinct bone in the orbit, segmented from the posterior part of the malar, and 

 probably the homologue of the lachrymal. 



7. The tympano-periotic bone fixed to the cranium by a posterior, long, wedge- 

 shaped (mastoid 1) process lying in a groove between the exoccipital and the squamosal. 



8. Number of vertebrae not exceeding 50; ribs not exceeding 10 pairs. 



9. Transverse processes of arches of dorsal vertebrae ceasing abruptly near the end of 

 the series, and replaced by processes on the body at a much lower level, and which are 

 in a line (or serially homologous) with the lumbar transverse processes. 



10. Spines of dorsal and lumbar vertebrae very long, transverse processes short, bodies 

 of posterior lumbar and anterior caudal vertebrae much elongated. 



11. Sternal ribs permanently cartilaginous. 



12. Pectoral limbs small, with a rounded extremity. The five digits all moderately 

 well developed. 



13. A small subfalcate dorsal fin, situated considerably behind the middle of the back. 



14. External respiratory aperture a single, transverse, median, subcrescentic opening. 



15. A pair of longitudinal cutaneous furrows on the throat, nearly meeting in the 

 middle line in front, and diverging posteriorly. 



By the majority of the above characters, and all the more important ones, as Nos. 1, 



' According to strict rules of priority, " Hyperoodontoid " would be the more correct term, as Hyperoodon 

 was the first genus of the group distinctly characterized ; but as the name is erroneous in its signification, and 

 not hitherto used, I have thought it better to keep to the more generally adopted and less objectionable term 

 of " Ziphioid " first applied by Gervais to the animals allied to the Cuvierian genus Zlphius. They constitute 

 Eschricht's Shynchoceti. 



