. Cephalopoda. Cephalopoda. 171 The general habitus closely resembles that of the young Alloteuthis shown in Figure 68 on p. 169. It has, however, some specific characters which will be described below. At any rate, it is a rather slender animal which swims or floats well and never rests on the bottom. All Loliginidae are strictly nektonic, although they live close to the bottom and shore and never move far from the surface or the shore. We assume that the ancestral form has the size of an average Loligo vulgaris which it may also resemble in FIGURE 72. Lateral view of the transpa
. Cephalopoda. Cephalopoda. 171 The general habitus closely resembles that of the young Alloteuthis shown in Figure 68 on p. 169. It has, however, some specific characters which will be described below. At any rate, it is a rather slender animal which swims or floats well and never rests on the bottom. All Loliginidae are strictly nektonic, although they live close to the bottom and shore and never move far from the surface or the shore. We assume that the ancestral form has the size of an average Loligo vulgaris which it may also resemble in FIGURE 72. Lateral view of the transparent posterior part of the shell of Alio te u this medla(20x). Optical section showing the small but distinct cone and the rudimentary rostrum situated dorsally on the cone. The rostrum resembles strikingly that of the Oegopsida (Ony- choteuthidae and Gonatidae; cf. Figure 63 on p. 150). An example are the lines which radiate like a fan from the posterior end of the cone and indicate the direction of growth: P — rhachis of gladius in optical section; C — cone, same; Sp — slit between diverging margins of flag; R — rostrum. The relationships between mantle and shell are shown mainly in Figure 69 on p. 169, which is an empty preparation of the situs of Loligo vulgaris. The gladius is situated entirely inside the mantle tube and has the general form that is characteristic for the Metateuthoidea. The gladius is covered anteriorly by the collar bond, i. e. the part of the primary mantle which is slightly cartilaginous and is situated opposite the neck cartilage. The mantle cavity extends posteriorly between the stellate ganglia, which are situated close together, as we had to assume already for Metateuthis (Figure 64 on p. 152). The anterior end of the gladius (Figure 62 on p. 146) is pointed, but the apex is very thin and delicate and often broken in preparations, which explains the inaccuracy of most illustrations. The thickened, longitudinally striped, gr
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Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectcephalopoda
