. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. 104 ACTINIARIA The mesenterial filaments are only present on the mesenteries of the first order. The ventral direc- tive pairs are, however, devoid of ciliated streaks. Below the aboral prolongation of the siphonoglj^he the filament namely begins as a weakly developed, single cnido-glandular streak of inconsiderable dimension, gradually growing thicker and attaining its largest dimensions in the reproductive region. As in certain Zoantharia (for instance Isozoanthns giganteus) and in the C
. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. 104 ACTINIARIA The mesenterial filaments are only present on the mesenteries of the first order. The ventral direc- tive pairs are, however, devoid of ciliated streaks. Below the aboral prolongation of the siphonoglj^he the filament namely begins as a weakly developed, single cnido-glandular streak of inconsiderable dimension, gradually growing thicker and attaining its largest dimensions in the reproductive region. As in certain Zoantharia (for instance Isozoanthns giganteus) and in the Ceriantharia the ciliated streaks have probably here fused with the aboral prolongation of the siphonoglyphe and the actinopharynx, though the diflterent parts of the filaments of the prolongation cannot be distinctly traced. Possibly the continuation of the sipho- noglyphe and the recurvated part correspond to the ciliated streaks, the folded parts to the cnido-glandular streak. The imperfect mesenteries are devoid of filaments. The ciliated streaks are of typical appearance. Only the mesenteries of the first cycle are fertile. The spe- cies is dioecious. The ovae are pro\-ided with a covering, decked by spines. lyarvae. (Sj'nonymj' and literature, compare Carl- gren 1906, p. 81). The larvae of this species, living on several hydroid- medusae, have been anatomically described before by my- self and by several other authors, wherefore I do not give any details of its anatomy here. The younger stadia with only 3 couples of mesenteries are disc-like (Carlgren 1906 fig. 6a). Somewhat older stadia are a little more rounded, still older ones are more elongated and acuminated in the aboral end, only in the adult animal the body is cylindrical. The ex- terior aspect of the lar^-ae in different stadia I have shown 1906 (textfig. 6). On the plate 1, figs. 21—29 I have completed tlie scries (all larvae sketched on the same {• scale). The arrangement of the tentacles I have described b
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