. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. CERIANTHARIA. 73 I have described above a Cerianthid with botrucnidae, Bo/riicnidi/er norvcgicus. Botnicnidae occur in this species on protoniesenteries 2 and 3, on the first quartette of nietameseuteries, and on tlie longest mesenteries of the second. Their position is tlie most aboral part of the mesenteries, that is to sa^-, thev occupy exactly the same position as in the larval forms described by van Beneden. In the first place as to the histological structure of the isolated cnidorage
. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. CERIANTHARIA. 73 I have described above a Cerianthid with botrucnidae, Bo/riicnidi/er norvcgicus. Botnicnidae occur in this species on protoniesenteries 2 and 3, on the first quartette of nietameseuteries, and on tlie longest mesenteries of the second. Their position is tlie most aboral part of the mesenteries, that is to sa^-, thev occupy exactly the same position as in the larval forms described by van Beneden. In the first place as to the histological structure of the isolated cnidorages, it is possible that in certain cases van Beneden may be right in his statement that they consist only of epithelium, in certain isolated cnidorages however I have succeeded in as- certaining bevond all doubt the presence of a mesogloeal por- tion (figs. 7, 8, PI. IV.). The stalked botrucnid-grapes also are otherwise constituted, according to my investigations, than as van describes. They are not simply an epithelial formation, the mesog 1 oea enters into the composition of these grape-like organs. That , the mesogloea of the mesentery is continued into the botrucnidae, ramifying like a tree and giving off a branch to each botrucnid-grape ( 11). The mesogloeal process passes through the grape-stalk and broadens out at the base of the berry forming a sort of cup or funnel. From this cavity thin threads apparently proceed in the direction of the un- attached side of the grape, though the course of such extremely fine threads is hard to follow. In any case the mesogloeal pro- cesses sustain the usual supporting cells, which cover the outside of the basal portion of the grape, and within the cavity lie the bases of the very large thick-walled nematocysts, which are set close together and project outwards towards the periphery of the grape. Between the thick-walled nenuitocysts lie the thin-walled ones, the .smallest of which are just below the free surface of
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