Ix. PRESIDENT'S ADDRESS. 



A. Fisheri, Egerton. Not uncommon in the Purbeck Beds of 

 Swanage. There is a nearly complete specimen of this fish in 

 the County Museum. The family ranges from the Lias to the 

 Purbecks, in fact throughout the whole of the Secondary Period, 

 but it did not survive into the Tertiary Period. 



Teleostei. This is the last and the most highly organised 

 Order of Fishes. The exo-skeleton usually takes the form of 

 overlapping scales, the free-portions of which are for the most 

 part smooth and rounded at the edges. The vertebral centra 

 are always ossified, each face is deeply concave, and the 

 primordial cartilage of the skull is more or less replaced by 

 bone. It is difficult to define the point of separation of this 

 Order from the Ganoids. The body is usually covered with 

 thin cycloid, or ctenoid scales. The gills are suspended in a 

 gill-cavity, covered by an operculum. Sometimes there are 

 scattered dermal-plates either of true bone, or as in the body 

 of the Ostracion, which is guarded by a carapace of hexagonal 

 scutes, calcified, but not of a bony structure, or like the File- 

 fishes, the bodies of which are covered with innumerable small 

 spines somewhat similar to the shagreen of the Elasmolranchii in 

 appearance, but not in structure. The pelvic-fins are either 

 abdominal, or placed in advance of the pectorals. There are no 

 fulcra on the fins as in the Ganoids. It is now abundant in 

 tropical and sub-tropical seas, and appears for the first time in 

 the Middle Eocene of Monte Bolca. Most Teleostei possess two 

 pairs of limbs, the pectoral and ventral-fins ; the latter are often 

 absent, the former only occasionally. An air-bladder underlies 

 the vertebral column. It is absent in a smalt number of the 

 group, such as the Blennies, the Flat-fish, the Sand-eels, and a few 

 others. Some have accessory respiratory organs, which enable 

 them to sustain life for a considerable time out of the water 

 under exceptional circumstances, such as droughts and rainless 

 seasons. 



Some Fish are ovoviviparous, eggs hatched within the body of 

 the parent ; without placental attachment. The young are able to 

 swim from the first moment of their birth with agility and 





