. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. 28 CERIANTHARIA. contains, besides supporting cells, principally nematocysts with coiled spiral thread (the length of the nematocysts varies greatly and may reach to 103 fi) and mucus cells. The nematocysts are more numerous in the upper part and the mucus cells in the lower part of the column where they are closely packed together. The ectodermal musculature of the column is extremely developed; for the size of the animal it is the most strongly developed longitu- dinal musculature that I
. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. 28 CERIANTHARIA. contains, besides supporting cells, principally nematocysts with coiled spiral thread (the length of the nematocysts varies greatly and may reach to 103 fi) and mucus cells. The nematocysts are more numerous in the upper part and the mucus cells in the lower part of the column where they are closely packed together. The ectodermal musculature of the column is extremely developed; for the size of the animal it is the most strongly developed longitu- dinal musculature that I have observed in any of the Ceri- antharia. The stomatodaeum has the same structure as in Arach- itanfliiis oligopodus. The ridges in the aboral part therefore are not supported by mesogloeal processes. The ectoderm is very thick and contains nematocysts of varies forms, now resembling those found in the column, now spirocysts, now thick-walled and granulated, larger (55—6o/i and smaller 31— 41 //). The siphonoglyph is of the usual structure with speci- ally numerous mucus cells on the boundary of the stomatodaeum. The ectodermal musculature of the stomatodaeum and sipho- noglyph is feeble but distinct. The mesenteries (Textfig. 5): The directive mesenteries are comparatively long. Protomesenteries 2 agree in appearance with the meta- mesenteries of the ist and 2nd cycle (In consequence of the animal's contraction all these mesenteries are somewhat folded. See diagram). The ciliated region is long, but so far as I have been able to see from the anatomical examination, the region of the cnido-glaudular tract is absent, as in A. oligopodus. On the other hand there is a craspedion region. They extend to about the same length as the hyposulcus and are sterile. Protomesenteries 3 are sterile and rather longer than the directive mesenteries; the ciliated tract region is ver)- short, the cnido-glandular tract region on the contrary very long and very wavy. The metamesenteries of
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Keywords: ., bookcentury1800, bookdecade1890, booksu, booksubjectarcticregions
