ARABELLA IRICOLOR. 395 



dental apparatus is symmetrical. Foot with a small dorsal lobe sloping outward and 

 upward, a short setigerous division, and a lanceolate inferior lobe. Besides the ordinary 

 spines is a specially strong pointed spine of a brittle nature. Bristles simple, winged, and 

 tapering. 



Grube (1879) apparently makes three genera of this, viz., Arabella, Grube ; Aracoda, 

 Schmarda ; and Maclovia, Grube ; the first being distinguished by the presence of four 

 pairs of jaws, whilst the others have five, thus forming two distinct groups. Both groups 

 are stated to have jaw I hook-like, but Arabella has the base serrated, all the jaws 

 toothed, jaw II asymmetrical (Ungleich), two maxillae, and a rudimentary dorsal cirrus. 

 On the other hand Grube gives to Aracoda of the second group a single buccal segment, 

 two maxillae (Kiefertrager), and according to Schmarda jaw II is symmetrical; whilst 

 Maclovia, Grube, has jaw II asymmetrical, as in Arabella, and three maxillae (Kiefertrager). 

 Considerable confusion, therefore, was introduced into this group by the distinguished 

 naturalist, probably from relying on erroneous descriptions. 



Ehlers, in his ' Florida Anneliden ' (1887), follows Grube's diagnosis, and places under 

 Aracoda those in which the bases of the maxillae are dentate. 



Arabella iricolor, Montagu, 1804. Plate LIV, fig. 4; Plate LXII, figs. 8-8 c — head and 

 teeth ; Plate LXX1V, figs. 5-5 d— feet ; Plate LXXXIII, figs. 2 and 2 a— bristles. 



Specific Characters. — Head somewhat flattened, bluntly conical, and with four eyes, 

 one on each side of the middle line, and very slightly in front of the others, which are 

 external and less conspicuous. Body 8 ins. to a foot long, firm, rounded, often thrown 

 into a spiral, and of an iridescent pinkish colour with a tinge of reddish from the blood- 

 vessels. It tapers posteriorly to a tail, which has four short cirri — two somewhat longer 

 dorsally, and two ventrally. First two segments evenly rounded, but the feet cause a 

 lateral dimple in the others. First segment narrower than the second dorsally. Proboscis 

 with maxillae strongly curved and massive at the base, which is articulated with two 

 tapering processes, the narrow posterior end joined to two long parallel blackish rods, 

 which gradually diminish posteriorly and end in slight enlargements. The great dental 

 plates have nine or ten recurved teeth. First antero-lateral plate has five teeth, the two 

 anterior far surpassing the rest in size. The posterior has the same number of teeth, the 

 first and third being largest. Mandibles cleaver-shaped, black, with a pale tip and an 

 oblique cutting edge of considerable length. The posterior process commences after an 

 abrupt shelf. 



The foot has a small dorsal lobe above the setigerous process and a larger lower 

 lobe. At the tenth foot the row of bristles passes from above downward and forward — 

 below the upper and in front of the posterior lobe. This continues to the tail, where 

 the line of the bristles is less oblique and the setigerous lobe more prominent. The 

 bristles are of two kinds : (1) a dorsal series with a gentle curve and long, finely tapered tips 

 with narrow wings, and (2) a series with shorter tips which have a more abrupt curve at 

 the end of the shaft, the free edge of the curve having about five serrations. Anteriorly 

 the foot has from five to seven spines, and by-ancl-by the dorsal region has a group (four 



