Gatiy Marine Laboratory ^ St. Andrews. 5G3 



Another species is the well-kaown Arabella tricolor of 

 Montagu ^ = A. tricolor (Leach) Johnston, (probably the 

 Arabella quadristriata of Grube), which abounds between 

 tide-marks in the Channel Islands and also occurs in the 

 south of England and on the west coast of Ireland. The 

 head is somewhat flattened, bluntly conical, an eye being on 

 each side of the middle line posteriorly and slightly in front 

 of the other, which is external on each side and less con- 

 spicuous. Maxillae short, broad posteriorly, strongly curved, 

 with massive bases serrated internally, which are articulated 

 witii two tapering processes, the narrow ends being joined 

 to two long parallel blackish rods which gradually diminish 

 posteriorly and end in slight enlargements. The great dental 

 plate has nine or ten teeth. The pair of plates immediately 

 anterior have five powerful teeth, the most conspicuous 

 being the first. The next in front has four teeth, the 

 anterior tooth being the largest. The most anterior con- 

 sists of a single long curved hook or tooth, the base of 

 which posteriorly touches the next plate. The mandibles 

 form long blackish wedges, with oblique anterior edges, 

 the outer part of which is translucent, hard, and brittle. 

 Though slight variations occur in the figures of Elders and 

 De St. Joseph representing the dental apparatus, yet they 

 show apparently identical structure. The figure of Ehlers ■\, 

 again, needs amendment, e. g. in regard to the maxillae. 

 The foot has a small dorsal lobe above the setigerous process 

 and a large lower lobe. At the 10th 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 bristles is less oblique and the seti- 

 gerous lobe more prominent. The bristles are of two kinds : 

 (1) a dorsal series gently curved and with long finely tapered 

 tips and narrow wings, and (2) a series with shorter tips 

 presenting a more abrupt curve at the end of the shalt, 

 the free edge of the curve having about five serrations. 

 Anteriorly the setigerous region has from five to seven 

 spines, and by-and-by the dorsal region has a group (four or 

 five) of small spines which pass to the base of the cirrus. 

 Posteriorly the dorsal group increases in size. So far as can 

 at present be ascertained, this species seems to agree with 

 Maclovia gigantea, Grube, as figured and described by Baron 

 de St. Joseph %. 



* Linn. Traus. vii. p. 82 (1802). 

 t Zeitscli. f. w. Zool. Bd. xxv. Taf. iii. fig. 33. 

 X Ann. Sc. Nat. 7' ser. v. p. 230, pi. ix. figs. 92-95. 



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