724 MR, c. TATE REGAN ON [June 19, 



Division 2. Batoidei. 



Family 1. Rhinohatidce. 



a, Pristince — Sclerorhynchus, Propristis, Pristis. 



b. Rhinohatince — Rhyncliobatus, Rhina, Rhino- 



batus, Discobatus, Trygonorliina, Astrodermus. 



Family 2. Raiidce. 



Raia, Psammobatis, Sympteiygia, 

 Oyclobatis. 



Family 3. Dasyhatidce. 



Xiphotrygon, Pterojolatea, Urolophus, 

 Dasybatis, IJrogymnns, Ptycliodus, Mylio- 

 batis, Aetobatis, Rhinoptera, Dicerobatis, 

 Ceratoptera, Ceratobatis. 



Series II. GHASMATOPNEA. 

 Order HOLOCEPHALI. 



Family 1. Pyctodontidce. 



Pyctodus, Rhynchodus, Paleeomylus. 

 Family 2. Squalorcdidce. 



Squaloraia. 



Family 3. Myriacanthidce. 



Myriacanthus, Chimseropsis. 



Family 4. Ghimceridce. 



Ganodus, Ischyodus, Edaphodon, Elas- 

 modus, Rhinocliim?era, Harriotia, Callo- 

 rliynchus, Chimsera. 



I am of the opinion that any attempt to apply the rule of 

 priority to the nomenclature of groups such as suborders, orders, 

 &c., unless it is convenient to do so, cannot succeed. To call the 

 Notidanoidei either Paljeonotidani, Diplospondyli, or Opistharthri 

 is to give a misleading idea of the chai-acteristics of the division. 



Although the Selachians may quite well be regarded as a sub- 

 class of the Pisces, it is not improbable that they will be generally 

 accepted as constituting a class distinct from the true Pisces 

 (Teleostomi) Avhen their characteristic peculiarities are more 

 widely known. 



The Selachii * may be thus defined : — 



Craniate vertebrates with jaws. Nasal organs paired blind 



* In the definition and classification of the Selachii I have left out of account the 

 Hetevostraci and their supposed allies, primitive fishes of Palaeozoic times, as to whose 

 positica in the system no two authors seem to agree. 



