216 PRIONOSPIO STEENSTRUPI. 



tliat the hooks commenced on the fifteenth segment, but Mr. Southern described them on 

 the twelfth bristled segment. When this feature was examined the specimens were 

 much injured, so that exactitude was not possible. They seemed to begin about the 

 fourteenth or fifteenth. 



The three forms mentioned above, viz. Malmgren's, Sars', and Claparede's, have 

 each distinctive features, yet some of these may be due to imperfections in observation 

 and to variation. Certainly the bristles and hooks are very similar. The occurrence of 

 mature females in Claparede's small form, also recently procured by Mr. Southern, would 

 seem to militate against its being a young annelid. Moreover, the silence in connection 

 with the cephalic ridge and the absence of eyes in it and also in Malmgren's species is 

 another source of dubiety. The Canadian, the Arctic examples procured by the 

 " Valorous," and the P. plumosa of Sars, all present such a ridge, and it is possible 

 Malmgren may have overlooked it, since in some it is inconspicuous, especially in the small 

 Irish forms, yet it is observable, as Mr. Southern 1 also testifies. Future investigation 

 may clear up the ambiguities connected with the several forms, and may even link them 

 together as variations of one species. 



Pjhonospio Steenstrupt, Malmgren, 1867. 



Specific Characters. — Cephalic region with a median ridge and no eyes. Body 

 elongated, slightly flattened, and having 100 or more segments. Pinnate cirri much 

 longer than the branchiee of the fourth and fifth segments, which have ovate-lanceolate 

 lamella3 on the dorsum. The inferior lamella in the anterior segments is sub-rotundate. 



Body terminates posteriorly in an anus with two cirri. Ten anterior segments have 

 capillary bristles in both divisions. Bristles of the posterior feet are considerably longer 

 and more slender. Hooks commence about the fifteenth segment. 



Colour in spirit pale. 



Synonyms. 

 1867. Prionospio Steenstrupi, Malmgren. Annul. Polych., p. 202, Tab. x, fig. 55. 

 1880. „ „ Langerhans. Zeitschr. f. wiss. Zool., Bel. xxxiv, p. 90, Taf. iv, fig. 3. 



1882. „ „ Levin'sen. Vid. Medd. Nat. Foren., p. 98. 



1893. „ „ idem. Kan. ' Hauchs/ Hft. v, p. 335. 



1894. „ „ Bidenkap. Norges Annul., p. 93. 



„ ,, }) Mcintosh. Ann. Nat. Hist., ser. 8, vol. xiii, p. 82, pi. 6, figs. 1 — 8. 



,) ,) „ Southern. Proc. Roy. Irish Acad., vol. xxxi, no. 47, p. 101. 



Prionospio Steenstrupt occurs off Iceland on a muddy bottom in 40 fathoms (Lovell). 



A Canadian form, apparently the Prionospio Steenstrupi, Malmgren, dredged by Dr. 

 Whiteaves in the Gulf of St. Lawrence, Canada, presents certain differences from 

 Malmgren's description, and approaches that described by Sars. It forms a useful com- 

 parison with the Irish representative. No complete example is in the collection and no 

 satisfactory fragment of the posterior end — all presenting signs of mutilation and 

 regeneration. The proboscis was extruded in every case, so that the snout was more or 

 less distorted, the protruded organ forming a button-like process on the end of a short 

 1 Mr. Southern kindly sent two specimens and thus enabled the figures to be made. 



