The Skeleton of the Fish 



modified persisted through life, the vertebrae being strung upon 

 it spool fashion in various stages of development. In the Cyclo- 

 stomi (lampreys and. hagfishes) the limbs and lower jaw are 

 still wanting, but a distinct skull is developed. The notochord 

 is still present, but its anterior pointed end is wedged into 

 the base of a cranial capsule, partly membranous, partly car- 

 tilaginous. There is no trace of segmentation in the notochord 

 itself in these or any other fishes, but neutral arches are fore- 



FIG. 42. Hyostylic skull of Chiloscyllium indicum, a Scyliorhinoid Shark. (After 



Parker and Haswell.) 



shadowed in a series of cartilages on each side of the spinal 

 chord. The top of the head is protected by broad plates. 



FIG. 43. FIG. 44. 



FIG. 43. Skull of Heptrcmchias indicus (Gmelin), a notidanoid shark. (After 



Parker and Haswell.) 

 FIG. 44. Basal bones of pectoral fin of Monkfish, Squatina. (After Zittel.) 



There are ring-like cartilages supporting the mouth and other 

 cartilages in connection with the tongue and gill structures. 



