NEMATONEREIS UNICORNIS. 455 



The foregoing are above the single strong brown spine. Below the spine are the 

 jointed hooks which have the dilated end of the shaft minutely serrate (Plate L XXXIV, 

 fig. 1 b). The ventral cirrus is now pear-shaped from the outward growth of a conical 

 process. The vascularity of the foot is great. 



At the twentieth foot (Plate LXXV, fig. 3 a) a single powerful brown spine supports 

 the setigerous region, which has similar bristles and hooks. A single large hook crosses 

 the spine obliquely from above and projects over the ventral cirrus. It has a broad 

 wing at the tip, and the main fang is large (Plate LXXXIV, fig. la). In the foot, 

 however, the secondary process above the main fang is not distinct. The dorsal cirrus 

 is more slender. 



At the fiftieth foot the dorsal cirrus is even more slender than in front, and has a 

 distinct granular (glandular) enlargement at its ventral base. A single group of winged 

 bristles emerges above the spine, their wings are narrower, curves less marked, and tips 

 very attenuate. Below the spine the jointed bristles have increased in strength, the distal 

 ends of the shafts are striated, and a few serrations occur on the edge of the wings 

 guarding the terminal piece. The whole region is less and its outline more convex (less 

 flattened). The powerful hook projects above the ventral cirrus— which extends beyond 

 the massive glandular pad as a blunt cone. In this foot a brush-shaped bristle (or two) 

 occurs amongst the dorsal bristles (Plate LXXXIV, fig. I c). 



Proceeding backward the dorsal cirrus becomes less, but the glandular swelling 

 remains at its ventral base. The setigerous region forms a broad cone with the tip of the 

 powerful brown spine at the apex. Dorsally is a small group of the two kinds of winged 

 bristles (larger uppermost, smaller below), and one or two brush-shaped. The jointed 

 hooks project further outward (are longer). The great hook has increased in strength, 

 and extends as far as the tip of the ventral cirrus, which is elongated and somewhat 

 lanceolate, whilst the glandular swelling has moved inward and is less. 



Reproduction. — Claparede, in his ' Grlanures ' (1864), observes that in the females ova 

 were only developed behind the sixty-second segment. The young Nematonereis has four 

 eyes, but two disappear, and Grravier thinks that the maxillary apparatus of this and 

 Lysidice resemble each other. De St. Joseph found the minute young pelagic. 



Habits. — It is fond of coiling itself in the vessel like a corkscrew, but this is probably 

 connected with its surroundings. 



This was one of the fruits of Prof. Ed. Grube's researches on the fauna of the 

 Adriatic and Mediterranean, published in 1840. 



Ehlers (1868) gives the species four eyes. 



The Nematonereis Sclimavdse of the ' Challenger,' l from the south of Pernambuco, 

 is a closely allied form, but does not appear to be identical, and like the British form 

 lives in mud (red). The same form would appear to range to St. Vincent, Cape Verde 

 Islands, and to Cape Town, at both of which places fragments were obtained by the 

 ' Challenger.' Schmarda found it in the Atlantic, and Willey in Ceylon. 



It would seem that the three species mentioned by De Quatrefages (1865) may be 

 varieties of the same form. 



1 ( Annelida/ p. 262, pi. xxxvii, figs. 6 — 8; pi. xviiiA, figs. 16 — 19. 



