42 PECTINARIA BELGICA. 



Walker on September 7th, 1882, numerous minute Loxosomas occurred in the grooves of 

 the three conspicuous glandular ridges (last branchial and first bristled segment) and a 

 few behind the lamellae for the anterior hooks. 



Pennant (1777) observes that this form, his Nereis conchilega, is an inhabitant of the 

 Sabella tubiformis, which he describes and figures in the same volume, the figure 

 resembling the tube of this or Lagis Koreni. Of the animal he writes: " Nereis with a 

 flat body, attenuated towards the tail ; pellucid ; about thirteen feet on each side ; about 

 the mouth a series of very fine filaments." 



Chenu's (1843 — 53, pi. ii„ fig. 1) figure of the tube of this species somewhat 

 resembles that of Amphictene auricoma. 



So far as can be observed the Sabella belgica of Dalyell (1853) appears to be this 

 species — both in regard to the account of the animal and the form and size of the tube. 

 He found it nocturnal in habit. 



Claparede (1868) reviews the structural features of the Neapolitan Pectinaria, the 

 hooks of which differed from those of the Northern form, and finds that the blood, as 

 Eathke states, moves from behind forward in the two large intestinal vessels, but this is 

 also the direction of the blood in the ventral vessel, whereas the current in the two dorsal 

 trunks is from before backward — a remarkable variation in the Polychsetes. Eathke 

 considered the whole series of glands in the anterior region assexual, those in front being 

 ovarian and those posterior testicular. He thus agreed with Pallas. 1 Claparede points 

 oat that these are not sexual glands and that the Pectinarians are unisexual. These 

 glands are ciliated externally and contain brownish-yellow concretions or cellular bodies, 

 and that such are homologous with the excretory structures in the Chlorsemidge. He 

 found a segmental organ at the base of the first branchia and in connection with the 

 second pair of glands mentioned above, and he thought it probable that the others had a 

 like function ; further, that Rathke may have been correct in seeing ova in their interior 

 at the time of reproduction — on their way to the exterior. He was uncertain as to the 

 exact place of origin of the sexual elements, though he saw minute ovules in the interstices 

 of the small muscles of the feet. 



Leschke 2 (1902) describes a pelagic larval stage captured in October which shows 

 prototroch and telotroch, pigment-specks in rows occurring over the snout in front of the 

 former and along its line. The mouth opens on a projecting process anteriorly, and the 

 shape in lateral view is peculiar. 



Considerable confusion existed in the writings of the earlier authors between 

 this species and Lagis Koreni, and such even held till the end of the nineteenth 

 century. The frequent occurrence of the latter form and the comparative rarity 

 of the former, as well as the paucity of reliable descriptions and figures, probably 

 had this tendency. In the Scottish seas Lagis Koreni generally frequents shallow 

 water on sandy beaches, whereas P. belgica has as a rule been only procured by 

 the dredge. 



1 ' Miscellanea Zoolog./ p. 130, and ' Dierkimdig. Mengelwerk/ IY Stuk, p. 20. 



2 ( Wissensch. Meeresuntersuch./ Bd. v, p. 127, Taf. vi, fig. 13. 



