LAGISCA EXTENUATA. 307 



those of Lagisca floccosa, which have longer spinous regions and a different curve at the 



tip. The ventral cirrus has well-marked clavate cilia. The segmental papilla is minute. 



In the presence of the pale specks on the scales it resembles the rare Polynoe nivea 



of Sars, 1 but the absence of cilia in the latter species and other characters distinguish it. 



4. Lagisca extenuata, Grube, 1840 (?). 



Specific Characters. — Length about one and a quarter inches in spirit. Head with a 

 deep median groove and two prominent peaks ; eyes comparatively large, two in front 

 of the nuchal collar, and two larger in front of the middle line, and lateral in position. 

 Median tentacle somewhat long, scarcely dilated below the filiform tip, and with 

 moderately long cilia. Lateral tentacles short, with attenuate tips. Tentacular cirri 

 similar to the median tentacle. Palpi have rows of minute conical papilla?. Scales fifteen 

 pairs, rounded in front, reniform posteriorly, densely covered with minute spines, and the 

 free edge is profusely ciliated. Dorsal bristles strong, slightly curved, and closely 

 spinous, with a smooth spear-shaped tip ; ventral with a bifid tip and close rows of 

 spines, the tips of some at the ventral edge being simple. Dorsal cirri somewhat slender, 

 with numerous and slightly tapered cilia with bulbous tips. Ventral cirri stout, with 

 short cilia. Segmental (nephridial) papilla scarcely distinct. 



Synonyms. 



1840. Polynoe extenuata, Grube. Actio. , Echin., u. Wurmen p. 86 (?). 

 1861. „ cirrata (0. F. M.), Grube. Ausflug nach Triest., p. 81. 

 1865. Lepidonotus Leachii, De Quatrefages. Ann., p. 258 ? 

 „ „ dumetosus, Ibid. Annel., t. i, p. 259 (?). 



1867. Lagisca Ehlersii, Malmgren. Ann. Polych., 9. 



1868. Polynoe extenuata, Claparede. Ann. Nap., 70, pi. ii, fig. 2. 

 1870. „ „ Supp., p. 372. 



1875. „ „ Marion and Bobretzky. Ann. Sc. Nat., 1875, p. 6. 



„ Lagisca extenuata, Marenzeller. Zur Kennt. Adriat. Annel., p. 5, Taf. i, f. 1. 



1876. „ Jeffreysii, Mcintosh. Trans. Z. S., ix, p. 397, pi. lxxi, f. 8, 9, 11, and 12; pi. lxxiii, 



f. 17 and 18. 

 1884. ,, extenuata, V. Cams. Fauna Medit., 202. 

 1888. „ „ De St. Joseph. Ann. d. Sc. Nat. (7), v, p. 180, pi. viii, f. 52—54. 



1890. „ „ Malaquin. Ann. Boulon., 22. 



1891. Polynoe (Lagisca) extenuata, Hornell. Op. cit., 12, pi. xiii, f. 4 and 8. 

 1898. Lagisca extenuata, De St. Joseph. Ann. d. Sc. Nat. (8), v, p. 237. 



Habitat.— A common Mediterranean form procured in the ' Porcupine ' Expedition 

 of 1869, in the tube of an Eunice, in 173 fathoms off the west coast of Ireland, and also 

 in a free condition on the same ground — muddy sand. Next year (1870) it was dredged 

 at the depth of 690 fathoms in the Atlantic (Channel slope). 



It is also a tidal form on the eastern border of the Irish Sea. 



1 ' Geol. og Zool. Eeise/ 1862, p. 39. 



