SYSTEMATIC ACCOUNT 201 



border of the third chaetiger. The prostomium is wider than long, with a straight anterior border 

 with two long dorsal and two short ventral antennae. Two eyes are present, but may not be visible in 

 specimens preserved in alcohol. Three pairs of tentacular cirri are present, one dorsal and one ventral 

 just behind the antennae and the third very small almost an appendage of the lower of these. The first 

 three parapodia have no ventral cirri but a linear series of stout simple chaetae thicker than those 

 from the fourth foot posteriorly; these have both compound and simple chaetae, grouped fan-wise 

 about a spatulate pedal lobe, and ventral cirri. The compound chaetae have a heterogomph articu- 

 lation and smooth, ovate terminal pieces. Dorsal cirri are long on the first three parapodia, thereafter 

 they are lanceolate; ventral cirri are small and subulate. 



Discussion. In 1919 Chamberlin described two new species, Lopadorhynchus nans, differing from 

 L. brevis in the arrangement of simple chaetae, and L. parvum which is without eyes. Neither of these 

 characters warrants specific separation. All species of Lopadorhynchus reported to have eyes lose the 

 ocular pigment when preserved in alcohol, and the arrangement of chaetae in the parapodia varies 

 from specimen to specimen within the same species. In describing L. nans, Chamberlin also referred 

 to ventral cirri which, however, are clearly post-setal lobes. 



General distribution. L. brevis has not been reported in large numbers from the South Atlantic 

 and appears only to the north of the Sub-Tropical Convergence (see pp. 259-261). 



Lopadorhynchus uncinatus Fauvel, 19 15 



Original localities. From off the Azores and Monaco. 



Lopadorhynchus uncinatus Fauvel, 1915, p. 3, fig. 2. 



Lopadorhynchus uncinatus Fauvel, 1916, pp. 57-61, pi. 1, figs. 2, 3, pi. 4, figs. 4-14. 



Lopadorhynchus uncinatus Fauvel, 1923, pp. 184-5, figs. 6ya-g. 



Lopadorhynchus uncinatus Fauvel, 19326, p. 75. 



Lopadorhynchus uncinatus Monro, 1936, pp. 1 13-14. 



Lopadorhynchus uncinatus Monro, 1937, p. 266. 



Lopadorhynchus uncinatus Wesenburg-Lund, 1939, pp. 10-12, figs. 6-7, chart 6. 



Lopadorhynchus uncinatus Treadwell, 1939, pp. 207-8, fig. 35. 



Description. This species measures up to 24 mm. long by 6 mm. wide, across the tips of chaetae, 

 for a maximum of thirty-two chaetigers. The body is divided into two distinct regions at the posterior 

 border of the second chaetiger. The prostomium is wider than long, pointed anteriorly with two long 

 dorsal and two short ventral antennae. Two eyes may be present but the ocular pigment frequently 

 disappears in alcohol; Monro (1936) for example, reported a specimen from ' Discovery ', St. 714 with 

 eyes, but these are not visible now. The first two pairs of tentacular cirri are long and subulate, lying 

 dorsally and ventrally, just behind the antennae, the third is rudimentary at the base of the ventral 

 pair. Parapodia of the first two chaetigers are much more prominent than the rest, they are large and 

 stout, with up to seven strong unidentate hooks, grouped terminally, surrounded by a ruff or collar 

 (possibly the modified ventral cirrus) and have a small dorsal cirrus: the whole foot is directed 

 laterally. The succeeding feet are directed backwards and are thin and paddle-shaped with stout 

 dorsal cirri and smaller ventral cirri with chaetae grouped fan-wise about the pedal lobe; both simple 

 and compound chaetae are present in the first of these chaetigers, but gradually the latter replace the 

 former entirely. The terminal article of the compound bristles is ovate with serrations on one side and 

 the articulation is heterogomph. Dorsal cirri are short and conical, ventral cirri smaller than these 

 and subulate. 



General distribution. L. uncinatus has frequently been recorded from the South Atlantic where it 

 has its southern limit of distribution at the Sub-Tropical Convergence (see pp. 259-261). 



