162 PISCES. 



a little in front of the transversely arched mouth. The skin is 

 rarely naked ; it is usually shagreen-like in consequence of the 

 osseous bodies which are embedded in it, or it may also be covered 

 with osseous plates and scutes. The palato-quadrate bar is moveable 

 and is separate from the cartilaginous cranial capsule. 



Tribe 1. Squalides (Sharks). Spindle-shaped Plagiostomes, with 

 lateral gill slits ; eyelids with free edges ; incomplete shoulder girdle, 

 without cranial fin cartilages. 



The body is spindle-shaped, carries the pectoral fins more or less 

 vertically, and ends with a powerful tail, which is bent dorsalwards 

 at the end. There are, however, forms which, with regard to their 

 body shape, are allied to the Rays, and constitute forms of transition 

 to the latter group, e.g., the genus Squatina. The teeth are usually 

 pointed and dagger-shaped, and placed in numerous rows. Tho 



FIG. 606. Chimcera monstrona (regne animal). 



families are distinguished principally by the number and position of 

 the fins, by the presence or absence of spiracles and of a nictitating 

 membrane, and also by the form and structure of the teeth. 



Fam. Scyllidae (Dog-fishes). Scyllium canicula L., the coasts of Europe. 



Fam. Cestraciontidae. Cestracion Pliilippi Blainv. 



Fam. Lamnidae (Porbeagles). Lamna glauca Mull., Henle ; Selache maxima 

 Gunn., reaches a length of thirty-two feet. 



Fam. Carchariidae. Carcharias glaucus Rond, the Blue Shark, with 

 umbilical placenta. C. lamia Risso. These two last are found in the Mediter- 

 ranean and the Ocean. Zygtena malleus Risso, the Hammer-headed shark. 



Fam. Galeidae (Topes). Galeus canis Rond., European seas ; Mustelus vulgaris 

 .and lavis Rond., with umbilical placenta, both are found in the Mediterranean. 



Fam. Notidanidae. Notidanus (Hexanchus) grucus Gm. and N. (Heptan- 

 chus) cinereus Gm., Mediterranean and Ocean. 



Fam. Spinacidse (Spiny Dog-fishes). Acantldas vulgaris Risso (fig. 603), 

 found from the northern seas to the South Sea. 



Fam. Squatinidae (Angel- or Monk-fishes). Squatina vulgar's Risso 

 squat ina L.) European seas. 



