. Cephalopoda. Cephalopoda. Concerning the relations between mantle and shell it should be noted that wearing off of the chromatophores in the adult shows not only the rhachis but also a large part of the flag under the skin (Figure 127b). The mantle thus almost retains its marginal attachment, and the shell is covered only by the shell fold. The fins are therefore still inserted entirely on the gladius and retain the primitive character in being completely separated. The fins approach their typical final form during postembryonic development, forming a blunt lateral corner and a typical "
. Cephalopoda. Cephalopoda. Concerning the relations between mantle and shell it should be noted that wearing off of the chromatophores in the adult shows not only the rhachis but also a large part of the flag under the skin (Figure 127b). The mantle thus almost retains its marginal attachment, and the shell is covered only by the shell fold. The fins are therefore still inserted entirely on the gladius and retain the primitive character in being completely separated. The fins approach their typical final form during postembryonic development, forming a blunt lateral corner and a typical "earlobe" at the anterior part of the base. The membranous connection which extends in the juvenile stage (Figure 133) to the posterior end of the body persists as a small membrane 271 (marked with a dotted line near x in the figure) near the posterior part of the base. The muscular rays originate on the relatively short base of the fin and radiate fanwise. The posterior end of the body is lengthened and contains the pointed cone; it widens anteriorly into the small and very shorty cup-shaped mantle sac. The mantle margin has a characteristic form, with the 3 typical corners, of which the dorsal is often slightly truncate; the margin is straight between the ventral corners and indented slightly more deeply lateral to them. There is also a blunt, slightly projecting corner on each side of the dorsal margin which is common also in other FIGURE 128. Same animal as in Figure 127, after removal of the ventral arms (cut at the base and at the connection with the buccal funnel at 10),mantle cavity opened. Natural size. Note in the arm apparatus: the characteristic base of the tentacle (17); the direct median connection of the ventral protective margins of the third pair of arms (18,15); above them, the communication between the ventral buccal pockets; laterally, the entrance to the circular canal (9); the cut connection between the ventral buccal pillars and the ventral a
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Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectcephalopoda
