SPIO FILICORNIS. 173 



1883. Spio filicornis, Levinsen. Nat. For. Vid. Meddel., p. 100. 



» 7> >, Wiren. Chaatop. f Vega ' Exped., p. 409. 



1889. „ „ Marenzeller. Arch. f. Naturges., Bd. lv, p. 132. 



1894. „ „ Bidenkap. Christ. Yid.-Selsk. Forhandl., p. 96. 



1896. „ „ Mesnil. Bull. sc. Fr. Belg., t. xxix, p. 129. 



1897. „ „ Michaelsen. Polych. deutsch. Meere, p. 152. 



1898. „ „ idem. Grcenl. Annel., p. 128. 



1909. „ Gattyi, Mcintosh. Ann. Nat. Hist., ser. 8, vol. iii, p. 165. 



„ „ filicornis, idem. Ibid., p. 162. 



1914. ? „ martinensis, Southern. Proc. Roy. Irish Acad., vol. xxxi, No. 47, p. 95. 



Habitat. — Swarming in sand near low-water mark, East Sands, St. Andrews. In 

 two fathoms off Symbister Harbour, Whalsay, Shetland. 



Head (Plate XCVIII, fig. 11) terminating anteriorly in a rounded point, from which 

 the central ridge passes backward to end in a papilla about the line of the second bristled 

 segment. Two minute black eyes occur (one on each side) in front of the papilla 

 posteriorly. The ridge is supported by the buccal segment, the sides of which are 

 bevelled anteriorly so as to give, from the dorsum, the snout a conical form. The long 

 tapering tentacle comes off on each side just outside the occipital papilla and the eyes. 



Body about an inch in length and proportionally stout, a little tapered anteriorly, but 

 more distinctly posteriorly, where it terminates in two broadly ovate cirri. The body 

 acquires its greatest diameter in the preparations just before tapering anteriorly to the 

 snout, Segments distinctly marked, and ranging from 55 — 65 in number. The gills 

 form a conspicuous feature in lateral view and throughout the whole length, though 

 they are especially so in the anterior half of the body. In the preparations they assume 

 different positions in regard to the vertical axis — now nearly upright, or with a curve 

 forward or backward, and again arched over the dorsum. Their proportional size is 

 noteworthy. 



The first foot (Plate XCVIII, fig. 11a) bears a richly ciliated gill of considerable 

 size dorsally, an elongate-ovoid superior lamella with about a third of the dorsal edge 

 free, the rest fused to the base of the branchia, and the ventral margin trending to the 

 body- wall. The dorsal bristles are of moderate length, curved upward and backward, 

 and finely tapered, the upper series, as usual, are the longer and more delicate. The 

 ventral lamella forms a prominent obtusely-ovate process, and the bristles are curved and 

 finely tapered. 



The second foot (Plate XCVII, fig. 9) is similar, but the upper lamella is broader, 

 whilst the lower has a tendency to turn upward and to show greater obliquity of its lower 

 margin. The interlamellar gap is deep and broad. 



The size of the branchia has increased at the tenth foot (Plate XCVII, fig. 9 a), and 

 it is richly ciliated on its inner and posterior borders. The superior lamella is more 

 flattened externally and less free superiorly. The bristles of this division form a dense 

 series, the dorsal curving as usual backward and upward, the rest backward, and to a 

 less degree upward. The ventral lamella has a tendency to a rhomboidal shape, with a 

 rounded inferior angle, and the dense tuft of bristles has its upper forms curved 

 downward at the point and the lower series curved upward. 



