. Cephalopoda. Cephalopoda. 158 for the later Belemnoidea (Naef, 1922, Fossile Tintenfische, particularly Figures 62 and 91). Neither the Teuthoidea nor the Sepioidea have hooks; both developed from an early form of Belemnoidea (Aulacoceratidae; see p. 135) which had only suckers and which was described as Protodecapus (p. 109—127) in general outline. No Proto- or Mesoteuthoidea had hooks; the statements of Miinster, Meyer, Wagner, Walther (p. 147) on this are erroneous. (Cf. also Zittel, 1885, Figure 713 on p. 519, which can be mis- leading; see also my book on the fossil Cephalopoda, loc. ci
. Cephalopoda. Cephalopoda. 158 for the later Belemnoidea (Naef, 1922, Fossile Tintenfische, particularly Figures 62 and 91). Neither the Teuthoidea nor the Sepioidea have hooks; both developed from an early form of Belemnoidea (Aulacoceratidae; see p. 135) which had only suckers and which was described as Protodecapus (p. 109—127) in general outline. No Proto- or Mesoteuthoidea had hooks; the statements of Miinster, Meyer, Wagner, Walther (p. 147) on this are erroneous. (Cf. also Zittel, 1885, Figure 713 on p. 519, which can be mis- leading; see also my book on the fossil Cephalopoda, loc. cit.) (157). FIGURE 66. a) Cross section through the posterior part of the body of a young Pterygioteuthis in the middle of the fins (diagrammatic, after Tippmar, 1913, p. 518, with interpretations). Note the pocket of articulation of the fins (without letter); the keel of the rhachis (Kl); the fin cartilage (Kr); the insertion of the muscular mantle on the outer side of the shell margin; the attachment of the funnel and the cepha- lopodial retractors (Mu) on the inner side of the shell margin, which is directed otherwise free toward the mantle cavity and is covered by the remnants of the primary mantle; the shell margin (Kt) which projects into the mantle cavity. b) Corresponding section through an older, higher form of Metateuthoidea. The gladius is surrounded by the muscular mantle to such an extent that only the keel is free under the dorsal skin. Lettering as in Figure 56 on p. 139. The muscular mantle has grown upward on the outer side of the shell in section b, forcing the base of the fin away from the shell sac and to the outer side of the muscular mantle; the base of the fin remains,however, unchanged in principle. See p. 163. The tentacles require particular consideration. In the recent Metateu- thoidea and in their fossil relatives (p. 143) they are specialized as described for Protodecapus (p. 117—12 0) and in this respect resemble the tentacles 144. Please note t
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