BRANCHIOMMA VESICULOSUM. 249 



1 909. Branchiomma vesiculosum, Fauvel. Bull. Inst. Oceanogr., cxlii, p. 43. 



„ Lo Bianco. Mitt. Zool. St. Neap., Bd. xix, p. 578. 



„ Fauvel. Ann. Sc. nat. 9 e ser., t. x, p. 210. 



„ Ehlers. Sudpol. Exped., p. 574 



„ Southern. Proc. Roy. Irish Acad., vol. xxxi, No. 47, p. 139. 



„ Fauvel. Campag. Scient. Monaco, xlvi, p. 317. 



„ Allen. Journ. M. B. A., vol. x, p. 641 . 



„ Southern. Irish Sc. Invest., No. 3, p. 49. 



„ Mcintosh. Ann. Nat. Hist., ser. 8, vol. xvi, p. 16. 



„ Bioja. Anel. Poliq. Cantab., p. 65. 



1913. 

 1914. 



}) 

 1915. 



)) 

 1916. 

 1917. 



Habitat.— South coast of Devon (Montagu), Yealm sand-bank, Rum Bay, etc., 

 Plymouth (Allen). Generally procured by dredging, but also is found between tide- 

 marks. West coast of Ireland (Southern). Elsewhere it: occurs in the Channel, Atlantic, 

 Mediterranean (Claparede), Madeira (Langerhans), Dinard (De St. Joseph), Naples (Lo 

 Bianco); Azores, Bay of Fayal (Fauvel), shores of Cantabria (Rioja), Simonstown (Ehlers), 

 St. Vaast-la-Hougue (Fauvel). 



Kolliker, 1 in 1858, constituted the genus Branchiomma for those Sabellids possessing 

 eyes on their branchiae, and he gave us a type, Amphitrite bombyx, Dalyell. Sars a little 

 later (1861) 2 made the genus Dasychone, characterised by the dorsal pinnules on the 

 branchiae. Claparede rightly restricts the term Branchiomma to those having sub- 

 terminal eyes, such as B. Kolliheri — the form which Kolliker probably studied. Dorsally 

 the cephalic plate presents a deep fissure between the firm basal pillars of the branchiae. 

 The somewhat deep collar arises from the outer edge of each pillar and slopes with an 

 unbroken edge downward and forward to the mid-ventral line, where a fissure separates 

 the two sides, each of which is produced into a prominent rounded edge which slightly 

 overlaps its neighbour. The adjoining first scute is indented in the middle line, thus 

 giving a character to the region. Whilst, therefore, the collar is largely developed 

 ventrally, a considerable part of the dorsum is devoid of it. De St. Joseph found two 

 pigment-spots (eyes) over the cephalic ganglia. An otocyst occurs on each side at the base 

 of the branchiae. The branchiae are of moderate length (one-sixth length of body, 

 Montagu), and their filaments are from eighteen to twenty-four in number. Each fila- 

 ment has the usual structure and tapers distally, ending in a subulate whitish terminal 

 process into which the chordoid axis, which is remarkably attenuate toward the tip, does 

 not go. The subulate terminal filament when no eye is present has a translucent thin 

 margin, especially at the commencement of its inner edge. It is at this region, viz. the 

 inner base, that the eye develops as a conspicuous dark brownish- violet organ, a stripe 

 of the flattened translucent margin connecting its inner base with the line of the pinnae, 

 whereas the distal part of the process is slender. The pinnae are very fine, of average 

 length, and provided with a chordoid unjointed axis. When injured these organs are 

 readily reproduced from the filament, to which they give a feathery appearance. When 

 the animal projects itself from its tube, the branchiae are gracefully spread like the flower 



1 ' Zeitschr. f. wiss. Zool./ Bd. ix, p. 536. 



2 f Vidensk. Selsk. Forhandl./ 1861, pp. 28 and 33. 



201 



