CASTALIA ABCTICA. 125 



H. Rathke (1843) formed a new genus and species for this form which he correctly 

 recognized as 0. F. Midler's Nereis punctata. 



Tauber (1870) merges the Psamathe punctata of Johnston in this species, but they 

 are distinct alike in minute structure, colouration, and habitat. 



2. Castalia arctica, Malmgren, 1867. Plate LVIII, fig. 14 — head; Plate LXIX, fig. 

 15— foot; Plate LXXVIII, figs. 3 and 3 a— bristles. 



Specific Characters. — Head somewhat square with two tentacles anteriorly and four 

 rather small eyes (reddish in spirit), the anterior pair wider apart. Tentacular cirri as 

 in Castalia fusca. The palpi are two-jointed. Body about half an inch long, some- 

 what fusiform, and terminating in two long anal cirri. Proboscis with a papillose rim 

 (ten papillse — Theel, Levinsen, etc.), the single example from the ' Porcupine ' not being 

 definite in this point. Two prominent brownish hooked maxillae, ventro -lateral in 

 position. Foot biramous, two slender spines passing into the ceratophore of the dorsal 

 cirrus, which is more or less segmented. No bristles are present in the division. 

 Setigerous region of the inferior division diminishes towards the tip, and has a conical 

 papilla in front of the tip of the spine. Bristles curved towards the tip of the shaft, 

 which is dilated and with a shoulder from which the terminal process proceeds. The 

 latter is slightly curved and diminished distally, has a serrated edge, and ends in a minute 

 claw with a secondary process beneath. Ventral cirrus comparatively short and 

 subulate. 



Synonyms. 



1790. Nereis aphroditoides, Fabricius. Fauna Grcenl., No. 278, p. 296. 



1867. Castalia Fabricii, Malmgren. Annul. Polychget., p. 32 (?). 



„ „ arctica, idem. Ibid., p. 32. 



1883. „ aphroditoides, Wiren. Chast. 'Vega' Exped., p. 401. 



„ „ Fabricii, Levinsen. Vidensk. Meddel. Foren. Kjobenh., p. 239. 



1889. „ aphroditoides, Marenzeller. Arch. f. Naturges., 55^ p. 128. 



Habitat. — Dredged in 90 — 125 fathoms fifty miles west of Valencia on the west coast 

 of Ireland by Dr. Gwyn Jeffreys. 



Sengiarak, Greenland (O. Fabricius). Siberia and Behrings Strait (Wiren). 



Head (Plate LVIII, fig. 14) somewhat square with the usual tentacles anteriorly 

 and four rather small eyes (reddish in the preparation), the anterior pair wider apart. 

 The tentacular cirri resemble those of Castalia fusca. The palpi are two-jointed. 



Body appears to be about half an inch in length, is somewhat fusiform in outline, 

 and terminates posteriorly in two long cirri. The proboscis, unfortunately, was injured 

 in drawing, so that its subsequent examination was unsatisfactory. It had a papillose 

 rim, but whether so many papillae occurred as in the figure is an open question. Two 

 brownish hooked maxillae occur ventro-laterally and project during the extrusion of 

 the cylindrical or barrel-shaped organ. 



The foot (Plate LXIX, fig. 15) is biramous, two slender spines passing into the base 



