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256 DODECACERIA CONCHARUM. 



1874. Dodecaceria concharum, Mcintosh. Ann. Nat. Hist., ser. 4, vol. xiv, p. 203. 



1875. Heterocirrus saxicola, Panceri. Atti Soc. Ital., vol. xviii, p. 526. 



„ „ ,, Marion and Bobretzky. Ann. Sc. nat., 6 e ser., t. ii, p. 67. 



j, Dodecaceria concharum, Mcintosh. Invert, and Fishes St. Andrews, p. 127. 



1879. „ „ Tauber. Annul. Danica, p. 120. 



1880. „ /, Langerhans. Zeitschr. f . wiss. Zool., Bd. xxxiv, p. 96, Taf. iv, fig. 8. 



1883. „ „ Levinsen. Yidensk. Meddel. Nat. Foren., p. 111. 



1884. „ „ Webster and Benedict. Bep. Comm. Fish and Fisheries U. S. A. for 



1881, p. 730. 



1885. Heterocirrus saxicola, Cams. Fanna Medit., p. 248. 



1888. Dodecaceria concharum, Cunningham and Bamage. Trans. Boy. Soc. Edinb., xxxiii, p. 647, 



pi. xxxix, fig. 12. 

 „ Bidenkap. Christ. Yet.-Akad. Haudl., p. 97. 



Monticelli. Boll. Soc. Nat. in Napoli., t. ix, p. 87 (1895). 

 „ Mesnil and Caullery. Comp. Rend. Acad. Sc, t. cxxiii, p. 511. 



„ Michaelsen. Polych. deutsch. Meere, p. 146. 



„ De St. Joseph. Ann. Sci. nat., 8 e ser., v, p. 346, pi. xx, figs. 160, 161. 



Journ. M. B. A., vol. vii, p. 228. 

 „ Southern. Proc. Boy. Irish Acad., vol. xxviii, p. 237. 



„ Elwes. Journ. M. B. A., vol. ix, p. 63. 



„ Mcintosh. Ann. Nat. Hist., ser. 8, vol. vii, p. 156. 



„ Southern. Proc. Boy. Irish Acad., vol. xxxi, no. 47, p. 119. 



Habitat. — Frequent under the roots of tangles (Laminaria digitata) especially when 

 these have a crust of Lithoth amnion beneath them, and in sandstone at the West Rocks, 

 St. Andrews. (R. and W. C. M.) ; Howth, Dublin, and various localities on the west 

 coast of Ireland (Southern) ; Torquay, in limestone boulders (Elwes). 



Abroad it has been procured in Finmark and the shores of the North Sea (Malmgren, 

 Tauber, etc.) ; Marseilles (Marion and Bobretzky) ; Adriatic (Grube) ; shores of France 

 (De St. Joseph) ; Atlantic coast, U.S.A. (Leidy, Verrill, Webster and Benedict) ; Madeira 

 (Langerhans). 



Head (Plate XCI, fig. 3) more attenuated than the rest of the body, the anterior 

 border being rounded, though capable of various changes of form. Mouth entering a little 

 behind the tip inferiorly as a Y-shaped slit in which the action of the cilia is marked. A 

 considerable amount of dark pigment occurs on the lips. The colour of the snout is dull 

 greenish. 



Body about an inch in length, slightly tapered toward the snout and more distinctly 

 diminished toward the tail; more or less rounded throughout. When the animal is 

 extended the anterior region of the body is nearly as narrow as the snout. Segments 

 sixty. The tentacles are twelve in number, arise on the dorsal surface opposite each 

 other, and the bases of the pairs approach quite as closely as in Heterocirrus ater. 

 They commence at the anterior part of the second segment, the first pair being longer 

 than the others. Dr. Johnston mentions the occurrence of eight. As a rule they are of 

 a pale green colour, with darker pigment at the tip, but they may be dull orange. A 

 coiled blood-vessel proceeds along the centre of each, and the edges are often crenated 

 under examination, and when stretched out frequently show a dilatation at the tip. No 

 cilia occur on them. When sickly the tentacles assume a dull brown hue. 



