SPIO. 171 



moderate length, and adhere firmly; an eye is on each side, at the inner base of the 

 tentacle. Body about half an inch in length, somewhat rapidly tapered anteriorly and 

 more gently posteriorly, where it ends with filiform cirri (only one of which is present). 

 Dorsal surface somewhat flattened, ventral rounded. No branchiae. Dorsal lamellae much 

 developed and foliaceous in front, especially the third. Winged hooks make their appear- 

 ance about the fifteenth bristled segment. They are slender, slightly tapered after the 

 backward curve to the throat, have a main fang, and a single spike on the crown. The 

 dorsal lamellae diminish greatly after the fifteenth segment, and in the posterior half form 

 small conical processes behind the setigerous papilla. The ventral division in the same 

 region is represented only by the hook-papilla. The dorsal bristles are capillary, finely 

 tapered, and curved backward. Posteriorly they greatly increase in length and slenderness. 



Synonym. 

 1909. Spio G, Mcintosh. Ann. Nat. Hist., ser. 8, vol. hi, p. 165. 



Habitat. — From the debris of the deep-sea fishing boats, St. Andrews, June 3rd, 1898. 



Head simply rounded in front forming a bluntly-pointed snout, with the mouth 

 opening a short distance behind the tip. The two tentacles are of moderate length, and 

 are often gracefully coiled. Moreover, they adhere much more firmly than usual in 

 such forms. An eye occurs in the preparation on each side at the inner base of the 

 tentacle. 



The body is little more than half an inch in length, rather abruptly diminished anteriorly, 

 and gently tapered to the posterior end, which has two cirri of considerable proportional 

 length, thus differing from Pygospio. The dorsal surface in front is somewhat flattened, 

 whilst the ventral is more or less rounded ; posteriorly both surfaces are more or less 

 rounded. The bristled segments number about sixty. It is a noteworthy feature that no 

 branchial process has been seen in the preparation, whilst the unusual size of the anterior 

 dorsal lamellae attracts notice. It may be that in the absence of branchiae, so rare in the 

 group, foliate organs have a compensatory function. 



The first foot has a fairly developed dorsal lamella, which increases in the second, and 

 in the third it forms a large foliaceous expansion. The size of these organs is conspicuous 

 for at least a dozen segments, though they diminish from the fourth backward. The some- 

 what angular foliaceous flap of the third bristled segment is a feature of much interest, 

 but whether in addition to these the species was furnished with branchiae could not, from 

 the state of the specimen, be determined. So far as could be observed the dorsal lamellae 

 between the sixth and twelfth are more or less ovate-lanceolate. The bristles in these 

 anterior segments have the typical arrangement and shape, the upper dorsal are longer ; 

 the ventral bristles are shorter and more slender, and the ventral lamella is apparently a 

 short cone. 



About the fifteenth segment (Plate C, fig. 12) the dorsal lamella has greatly 

 diminished, though the dorsal and ventral bristles follow the type in front, and winged 

 hooks make their appearance, and continue to the posterior end. The shaft of the hook 

 is slender (Plate CV, fig. 12), has a well-marked backward curve below the wings, tapers 

 a little to the throat, from which the main fang comes off at a right angle, and apparently 

 only one spike occurs on the crown. 



