160 



Leodicidce from Fiji and Sanioa. 



Genus ARABELLA Gnibe. 



A. E. Grube, Die Familien der Anneliden, etc., 1851, p. 45. 



Body elongated, slender, without prostomial appendages or gills, with rudimentary 

 dorsal and anal cirri. No compound, pectinate, or hooked setae. Eyes often present 

 on the prostomium. Maxilla with long slender carriers, forceps, and 4 or 5 pairs of 

 toothed plates which may or may not be symmetrically arranged on the two sides. 

 Mandible well developed, the shafts pointed and well separated. All jaw apparatus 

 very dark in color. 



Arabella may easily be distinguished from Lunibrinereis, which it resembles very 

 closely in general appearance, by the fact that the first somite forms the posterior 

 border of the mouth, instead of the second, as in Lumbrinereis. In structure of the 

 jaw Arabella resembles Drilonereis, but the maxillary plates are larger and may be more 

 numerous, and the mandible is always more developed than in that genus. 



Arabella dubia, new species. 

 Plate 7, figures 11, 12; plate 8, figures 8, 9; text-figure 52. 



The type is from Pago Pago Harbor, Samoa, and is about 70 mm. long, with a 

 prostomial width of less than 0.5 mm. An incomplete specimen found in mud in 

 Suva Harbor, Fiji, is mucli larger but is badly preserved, so that measurements are 

 of little value. It is possible that the type 

 may be immature. The body is very irides- 

 cent. One preserved specimen from Pago 

 Pago shows transverse brown bands on the 

 somites, while the other is colorless. 



The prostomium (plate 7, fig. 11) is elon- 

 gated sugar-loaf in form, its length about one- 

 third greater than its width. There are two 

 pairs of eyes, the inner pair lying close to- 

 gether near the posterior border of the pros- 

 tomium, and easily seen; the second pair are 

 much less easily seen and lie one on either 

 side, at a little more than half the distance 

 from the corresponding inner eye to the pros- 

 tomial border. The first somite is a little 

 wider than the prostomium, but about two- 

 thirds as long. Its anterior margin is notice- 

 ably recurved. 



The parapodia are well developed from the 

 beginning. They have the form usual in this 

 genus, with a rounded setal lobe and a finger- 

 shaped posterior one. There is a single, rather 

 prominent, yellow-colored acicula, rounded 

 at the apex. The setae (text-fig. 52) are 

 broadened and bent toward the apex, this 

 bent region striated. Along the convex 

 margin is a narrow wing. A denticulation 

 along the margin of the wing is very marked 

 in some and barely discernible in others 

 very small. 



There are two pairs of stout anal cirri (plate 7, fig. 12). The maxilla is jet-black 

 with long carriers, not all of which are sho^vn in the figure (plate 8, fig. 8). On the 

 basal portion of the right forceps are 7 prominent teeth, with smaller denticulations 

 at the base. In the forceps figured, the right half has a bifid apex which apparently 

 is not present in the other specimen at my disposal and is probably an individual 



54 53 

 Text-Figures 52 to 56. 



52. Simple seta of Arabella dubia X 

 250. 



53 to 55. Drilonereis lumbricus. 53, 

 simple seta X 185; 54, acicula X 185; 

 55, acicula X 185. 



56. Simple seta of Drilonereis paiici- 

 dentata X 500. 



The number of setae in each somite is 



