SKELETON OF SKATE 



593 



through which the spinal cord passes, two condyles working 

 on the end of the vertebral plate, a large ear capsule on 

 each side posteriorly, a similar nasal capsule on each side 

 anteriorly, a long rostrum in front, two fontanelles on the 

 roof. Compared with the skull of a cod or of a higher 

 Vertebrate, that of a skate is simple ; it is not ossified, nor 

 divided into distinct regions, nor has it anything corre- 

 sponding to the investing membrane bones, W'hich in higher 

 animals are added to the original foundations of the skull, 



h hr.Z. 



FlCr. 



334. — Side view of skate's skull. 

 —After W. K. Parker. 



/.I, 



First labial cartilage ; n.c, nasal capsule ; a.o., antorbital ; 

 p.pt.q., palato-pterygo-quadrate ; M.c, Meckel's cartilage ; 

 h.m., hyo-mandibular ; e.h., epi-hyal ; c.k., cerato-hyal ; //./;., 

 hypo-hyal ; /;.6r.i-5, hypobranchials ; f.br., ceratobranchial ; 

 <'.6r., epibranchial ; ^.6;'.i, first prebranchial ; /./;., iuter-hyal; 

 m.pt., meta-pterygoid ; 2, 3, 7, foramina of exit of the corre- 

 sponding nerves. 



nor do the visceral arches in the skate take part in forming 

 the skull, which arises, as usual, froqi parachordals, trab- 

 eculae, sense capsules, etc. 



The visceral arches are primitively supports for the 

 wall of the anterior part of the food canal, but the first two 

 of them are much modified in connection with the jaws. 



The upper jaw of the skate is a strong transverse bar, 

 formed from the union of two palato-pterygo-quadrate 

 cartilages. The lower jaw is a similar bar formed from the 

 union of two Meckel's cartilages. 



38 



