POLYDORA QUADRILOBATA. 209 



A specimen, Polydora caeca, of (Ersted, mounted on a slide, was kindly sent by Col. 

 Elw-es from Babbacombe. (Ersted distinguishes it anteriorly by " rostro capitis in duas 

 appendiculas acuminatas producto, oculis nullis " ; fifth segment six to seven "aciculi," 

 whereas L. ciliatum, Johnston, has " rostro lobis rotundatis," " oculis quatuor, aciculis 

 11—12." Nothing can be made out of (Ersted's figures of the hook and bristle 

 (Tab. IT, fig. 16). De St. Joseph's important points of the same form are : " Colourless or 

 faintly yellow. Head with remarkably small, median bifid prow, no eyes ; four to six 

 acicular bristles with curved obtuse points, having two rudimentary spurs," as Claparede 

 figures in Polydora cornuta, Bosc, though he met with an example having the bristles of 

 one side with only one rudimentary spur (croc). They are accompanied by peculiar 

 bristles " boulette." So far as can be made out these are certainly less acute than in a 

 fresh Polydora ciliata, but the action of the calcareous rocks may have affected them. 

 There is nothing distinctive in Willemoes-Suhm's : account, and as his figure has what 

 appears to be branchiae from the first segment backward (except the fifth), there may have 

 been misapprehension. Carazzi is therefore in all probability right in joining Polydora 

 cxca to another form, viz. P. flava, and so far as could be seen in the specimen from 

 Babbacombe it could not be separated from P. flava. 



3. Polydora quadrilobata, Jacobi, 1883. Plate XCVIII, fig. 13— caudal region; fig. 17- 

 foot; Plate C, fig. 9— fifth foot; Plate CVI, figs. 4— 4 c— bristles and hooks. 



Specific Characters. — Head with smaller prostomial lobes than in P. flava, and the 

 ridge goes backward to the fourth bristled segment. The snout differs from most of the 

 other forms in its conical outline, for the peristomial supports taper anteriorly. Body 

 typical so far as the imperfect example shows, though posteriorly the terminal process 

 is four-lobed. Branchiae commence on the seventh bristled segment. The fifth foot is 

 distinguished by the large size and conspicuous condition of the dorsal capillary bristles, 

 which have the tips bent at an angle to the shaft and tapered to a fine point, with wings. 

 The large hook-like bristles dilate from the base to the last third, then slightly diminish 

 to the throat, from which a short tip comes off at considerably more than a right angle and 

 soon ends in a bifid stumpy point. The winged hooks commence on the seventh bristled 

 segment, and in their structure do not present any diagnostic feature of note. 



Synonyms. 



1883. Polydora quadrilobata, Jacobi. Anat. Histol. Untersuch. Wissenfels, p. 1. 

 1887. „ „ Eisig. Monogr. Capitell., p. 335. 



1896. „ „ Mesnil. Bull. sc. Fr. et Belg., t. xxix, p. 236. 



1897. „ „ idem. Ibid., t. xxx ; p. 87, pi. iii, figs. 9— 11. 

 „ w „ Michaelsen. Polych. deutsch. Meere, p. 44 



1909. „ „ Mcintosh. Ann. Nat. Hist., ser. 8, vol. iii, p. 170, pi. v, fig. 2. 



In Lithothamnion, dredged in Bressay Sound, and obtained between tide-marks at 

 Lerwick (W. 0. M.), July, 1871. 



Abroad it has occurred at Kiel (Jacobi) ; German waters, Sound, and Belt 

 (Michaelsen). 



1 'Zeitschr. f. wiss. Zool./ Bd. xxiii, p. 348, figs. 4—5. 



150 



