海星及び海膽に於ける極めて珍奇な異常輻の例

スポンサーリンク

概要

論文の詳細を見る
In the foregoing text are described the following specimens showing rather unusual sorts of abnormalities: A large specimen of Oreaster nodosus (L.) with one ray (R IV) bifurcated very close to the mouth (Pl. I, figs. 1-3). One of the branches is turned dorsad, so as to form a supernumerary arm lying a little higher than the level in which the other arms lie. The ambulacral groove of the arm in question forms a tunnel making its way throuth the disc, before reaching the free arm (textfig. 1). A rather large denuded shell of Mespilia globulus (L.) (Pl. II, figs. 5-7). One of the ambulacral zones is bifurcated on its course from the mouth to the apical area (fig. 8). From lack of the madreporic plate one can only tell that the zone in question is either the radius III or IV. Whether there existed an excessive ocular plate cannot be decided also from the defective state of the specimen (fig. 9). A medium-sized specimen of Colobocentrotus mertensii BRANDT with its long and short axes interchanged (Pl. II, figs. 10, 11). Normally the diameter drawn along the rays III-5 is the shortest in this species, whereas in the present case the shortest axis falls near the rays II-4 (textfig. 2). In other words, the long and short axes of the abnormal specimen lie at right angles to the corresponding ones in the normal state. The number of plates as counted along each row is altered accordingly, i. e., along the rows at or near the long axis the number is increased, and vice versa along the short axis. A description of another specimen of the same species with four rays is appended (Pl. I, fig. 4).
社団法人日本動物学会の論文
1939-03-15

著者

関連論文

もっと見る

スポンサーリンク