Selachii

I still remember my absolute shock on reading a interview in Locus, where he mentions that Selachii is the family name for sharks, and Venturi is the name for the nozzle of a jet, so that the two leading families of Ankh-Morporke are the Sharks and the Jets.

3:10 to Yuma Rogers 2008

It is still found in many of the Selachii and Amniotes.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

In the fishes we find an essential and considerable modification of the five vesicles; it is clearly the brain of the Selachii in the first place, and subsequently the brain of the Ganoids, from which the brain of the rest of the fishes on the one hand and of the Dipneusts and Amphibia, and through these of the higher Vertebrates, on the other hand, must be derived.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

It is the same with the cutaneous teeth or placoid scales of the Selachii.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

All these essential parts of the middle ear originate from the first gill-cleft and its surrounding part; in the Selachii this remains throughout life an open squirting-hole, and lies between the first and second gill-arch.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

Selachii, especially in the yelk-wall -- the border zone of the germinal disk in which the embryonic vascular net is first developed.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

He further showed that the branchial arches of the Selachii prove that their skull originally consisted of a large number of (at least nine or ten) provertebrae, and that the cerebral nerves that proceed from the base of the brain entirely confirm this.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

In the Selachii an arterial cone is developed from the foremost end of the ventricle, as a special division, cut off by valves.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

The foremost section, which is turned towards the ventral side, and from which the aortic arches rise, reproduces the arterial bulb of the Selachii.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876

Selachii six or seven pairs, most of the fishes only four or five pairs.

The Evolution of Man — Volume 2 Ernst Heinrich Philipp August Haeckel 1876