336 NEREIS (NEREILEPAS) FUCATA. 



Cunningham 1 denies that the neural canals are colossal nerve-fibres. He thinks they 

 are supporting structures to prevent the nerve-cords being bent at sharp angles. The 

 canals attain greatest development in worms which are extremely long; and further, 

 in these the nerve-cords are not separated from the epidermis, and therefore are more 

 exposed to danger. The neural canals have a position in relation to the nerve-cords 

 and ventral blood-vessel which is similar to that of the notochord in relation to neuro- 

 chorcl and aorta. 



H. Parlin Johnson (1901) considers the Alitta Brandti of Malmgren and Ehlers, and 

 the Nereis foliata, Baircl, the same species, and observes that the Pacific examples grow 

 to the length of 50 cm. with a diameter of 25 mm. He had not seen an epitokous form. 



Such types as the Pseudonereis gallapagensis of Kinberg from the shores of Peru 

 and the Galapagos Islands show the same leaf -like dorsal cirrus, and probably the same 

 vascularity. 2 



9. Neeeis (Neketlepas) fucata, Be Blainville. Plate LII, fg. 6; Plate LXI, figs. 6, 6 a 

 —head; Plate LXXIII, figs. 3-3 c— feet; Plate LXXXI, figs. 8-8 b— bristles. 



Specific Characters. — Head of the typical shape, with two subulate tentacles in front. 

 Eyes black, comparatively large, the anterior pair somewhat wider apart and occasionally 

 larger. Tentacular cirri of moderate length. Palpi white, only the distal process being 

 pale. Body 4 — 9 ins. in length, and segments 95 to 110. Peristomial segment wider 

 than the succeeding. The slender tail has two long cirri. The general hue is buff, 

 enlivened by two white streaks on the dorsum, with the red dorsal vessel between, and a 

 dotted white line along each side. The median white lines begin at the base of the 

 tentacles, enlarge before reaching the eyes, between which they pass, and again contract 

 on the first segment. The last segment has a conspicuous white patch. Ventral surface 

 pinkish buff. The proboscis has dorsally on its maxillary (distal) segment in extrusion a 

 group of somewhat large paragnathi (II) on each side at the base of the jaw. In the 

 space between them a single tooth (I) sometimes occurs. On the ventral surface two 

 groups of paragnathi (IV) also are found, the long axis being oblique, whereas that of the 

 dorsal series is more nearly transverse. Between them in the middle line posteriorly are 

 a few paragnathi (III) arranged transversely. The basal division of the organ has on the 

 eminence in front of each palpus a group (VI) of five or six small paragnathi. Ventrally 

 a row of larger paragnathi in groups of two to four (VII and VIII) occurs in front of the 

 area, and there are groups of minute ones behind, a long interval existing between the 

 dorsal groups and these. The strongly curved maxillse have from thirteen to sixteen teeth. 



First foot chiefly noteworthy for the large size of the dorsal cirrus. Whilst the 

 dorsal lobe in this is bluntly rounded, it gradually increases in size from the tenth to the 

 twenty-seventh, where it forms a great dorsal lamella, pointed externally and rounded 

 internally, the dorsal cirrus projecting from the upper border. Superior setigerous lobe 

 amalgamated with that beneath it, the bristles passing out in front. The second lobe is 

 ovate or ovato-lanceolate. Inferior setigerous lobe bifid, the longer and smaller papilla 



1 Op. cit., p. 275. 



3 C. Gravier, ' Arch. Zool. exper./ t. x, p. 629, pi. xvi, figs. 15—20, 1909. 



