A treatise on zoology . Fu;. 1-20. Skull ?uul visceral arches of FMm, ventral view. (After Gegenbaur.) a-v, antorbital process ,.,,/, cSoumlSrancW 4sihyal; c?>5, mth ceratobranchia ;/.b ^ypobranc^^^^^^^^^^ hyoinandibular ; I, labial; ,, Meckels cartilage ; m, nasal capsule , pb, pharjngobranclual,/./, palato-quadrate ; r, rostrum. ac(iuired, and it seems more reasonable to suppose that the Squatinidaerepresent an early offshoot from near the base of the Rajiform stemThey were represented in Upper Jurassic times by a well-differentiatedspecies, iiqiiatina speciosa, differing from the mode
A treatise on zoology . Fu;. 1-20. Skull ?uul visceral arches of FMm, ventral view. (After Gegenbaur.) a-v, antorbital process ,.,,/, cSoumlSrancW 4sihyal; c?>5, mth ceratobranchia ;/.b ^ypobranc^^^^^^^^^^ hyoinandibular ; I, labial; ,, Meckels cartilage ; m, nasal capsule , pb, pharjngobranclual,/./, palato-quadrate ; r, rostrum. ac(iuired, and it seems more reasonable to suppose that the Squatinidaerepresent an early offshoot from near the base of the Rajiform stemThey were represented in Upper Jurassic times by a well-differentiatedspecies, iiqiiatina speciosa, differing from the modern Rlmia chiefly inthe possession of fewer calcified concentric lamellae m the vertebrae(A. S. Woodward [503]). Sqnatma, Bel. ; to Jurassic, Europe. Rhina, Angel-fish, Klein ; tropical and temperate seas. 158 SELACHII Tribe 2. The pectoral fins fuse in front with the sides of the head, andthe branchial openings are quite ventral. The rostium, as a. Skeleton of \a ImJis, L. (From Owen, Anat. of Vcdeh,;, by permission of Messrs. Long-mans and Co.) 7, scapular region of pectoral girdle ; S, 9, 10, segments of anterior axis ofpectoral tin; 11, posterior axis; 12, radials of expanded pectoral fin; V^, preorbital process :52, cartilage plate joining scapula to vertebral column ; 50, posterior outgrowth of pectoralgirdle; ,;pelvic girdle ; 03, basipterygium ; c, anterior enlarged radial; v, pelvic-fin radials. rule, is much developed. In this division most of the changes inthe skeleton described above (p. 154) are carried out. Extra-brauchials are preserved in the Rhinobatidae and in Trygon. Theiliac process may be much developed; since it is large in theHolocephali and in the Tetrapoda, this is possibly a primitivecharacter. RAJIFORMES 159 Except in the first two families, the nostrils are confluent withthe mouth, there heing a well-marked fronto-nasal ])rocess. Although the main trend of the evolution of this Division
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