. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. HYDROIDA II 149 throughout three hydrothecte between the origins of two branches on the same side of the stem; in the two smaller colonies, on the otlier hand, the uuiuber varies from two to five, but these colonies are at the sauie time irregular in the wliole de\elopment of the branches in several places. The divi- sion of the branches into internodia is highly irregular; there ma\- be from two to nineteen livdrothecte on the branch internodia. The hydrothecae are set in two opposite row
. The Danish Ingolf-expedition. Marine animals -- Arctic regions; Scientific expeditions; Arctic regions. HYDROIDA II 149 throughout three hydrothecte between the origins of two branches on the same side of the stem; in the two smaller colonies, on the otlier hand, the uuiuber varies from two to five, but these colonies are at the sauie time irregular in the wliole de\elopment of the branches in several places. The divi- sion of the branches into internodia is highly irregular; there ma\- be from two to nineteen livdrothecte on the branch internodia. The hydrothecae are set in two opposite rows; their symmetrical plane coincides with the broad plane of the bran- ches, which is everywhere vertically placed, i. e. parallel with the axis of the stem. The distance between two hydrothecce on the same side of the branch is very great, as a rule about i''2 times the length of the h\'drotheca itself. The h\drotlieca (fig. LXXIX) is not particularly deeply imbedded in stem or branches; the distal third of the adcauline wall is free; the free part of the adcauline wall is straight, or not infrequentlv curving .slightly upward. The opening plane of the hydrotheca is pa- rallel with the branch The aperture is round, the margin exhibits indication of a pair of broad lateral teeth, further accentuated by the abcauline sinus in which the large single opercular plate is fastened. The structural character of the polyp it was impossible to investigate, owing to the state of preservation of the material. These colonies appear in the main to agree with the Pacific species Thujaria distans established by Fraser (1914 p. 197, pi. 32, fig. 123). There are, however, lacunae in Eraser's description, so the identity cannot be determined with certainty. Eraser's species has often secondarv dichotomous ramification of the branches; Thujaria?,^. iiii. dista,is from "Ingolf St. 85. this must be considered as due to difference in age. On the other hand, the hydro- part of a branch. th
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Keywords: ., bookcentury1800, bookdecade1890, booksu, booksubjectarcticregions
