EXPLANATION OF PLATE X. 



Fig. I. — Diagram, to scale, of the skull of C. orissa: &.6\ = brain 

 case; /./. = lower jaw; w./.=upper jaw; c.f. = cephalic 

 fin; o.c, = occipital condyle; /;w. = hyomandibular ; 

 w.c. = nasal capsule; ^, == sclerotic cartilage; o.p. = 

 prolongation of the cartilage towards the eye (sheath for 

 optic nerve); sc. = scapula; co. = coracoid; /. = junc- 

 tion of hyomandibular with the cranium : the branchial 

 arches have been omitted ; the cranium proper is shown 

 in thick outline : a and b = denticles of the skin from 

 above and from the side. 



,, 2. — Diagram, to scale, of the head of C. orissa; figures re- 

 present centimetres. 



,, 3. — Cranium of Aetohatis narinaria showing well-defined 

 orbits : 0. = orbit; e. = eye; c.f. = cephalic fin. 



