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Show 734 m r . c. t a t e r e g a x o n [June 19, Text-fig. 115. Mandibular and liyoid arches of a Pleurotreme (A) and a Hypotreme (B). A. Squatina angehis (after Gegenbaur). B. Haia clavata (after Parker). pt, pterygo-quadrate; p , palato-basal process; in, meclrelian cartilage; 7i, hyo-mandibular; c, cerato-hyal; b, basi-hyal; r, cartilaginous branchiostegal rays. minant. These terms have no practical application ; both groups include types in which the secondary calcification of the vertebral centra has no laminar structure (e. g. Rhynchobcitus, Oxyrhino), and others in which it is deposited as a series of concentric laminae (Squatina, Cetorhinus) ; also in both are forms in which the calcification presents a radiating pattern in cross section (e. g. Narcine, Orectolobus). In order to arrive at a natural arrangement of the Euselachii I have studied at any rate the more important of the numerous memoirs dealing with their anatomy, and wherever possible, and |
