LANICE CONCHILEGA. 143 



Reproduction. — The development of this species has been worked out by Claparede 

 (1863) from a larval form 0'26 mm. long to a fairly late stage with two branchiae, whilst 

 the same author and Mecznikow filled in the earlier stages in what is probably the same 

 form (their Terphella Mechelii.) Neapolitan examples are mature in August and September 

 (Lo Bianco). Southern (1914) dredged young specimens in May on the west coast of 

 Ireland. 



Pallas examined the anatomy of this form and his account was fairly accurate, though 

 in regard to the reproductive organs he thought that the ovary terminated by a medial 

 orifice at the edge of the first abdominal band. 



Claparede's l (1863) youngest stage in the development of Lanice conchilega occupied its 

 pelagic tube, and had seven segments, but was only 0*26 mm. in length. It showed a 

 horse-shoe-shaped anterior end with mouth and lower lip, a clavate median tentacle and 

 an eye on each side. The two segments succeeding the cephalic plate were devoid of appen- 

 dages, but the fourth had a process on each side with two bristles, and, moreover, 

 contained a circular sense-organ (his Gehorblasen). The next segment had a setigerous 

 process and two bristles as well as a flask-shaped ventral cirrus, and the following (sixth) 

 had only the latter. The terminal segment had palpocils and cilia at the vent. The 

 oesophagus, stomach and intestine were distinct." He followed the development through 

 various stages up to one with fifteen pairs of bristle-bundles, but still in the transparent 

 tube. The median tentacle of this was very long, and three others were developing at 

 each side. The statocyst had advanced forward and the two segmental organs were in 

 front of it, the author considering these were glandular organs for secreting the tube. 

 The flask-shaped ventral cirri extended from the third bristle-tuft for twenty segments. 

 Between this stage and a young form of 5 mm., in which most of the adult characters 

 except the third branchia were present, there is a gap, for the four eyes of the younger 

 form have disappeared, and a series in a row behind the collar have taken their places. 

 In the same way the flask-like ventral cirri with a hook at the tip have vanished and 

 tori are in position. Many segments are present, and the tentacles stretch beyond the 

 posterior end of the body. 



At St. Andrews young forms occur in tubes on the blades of Laminaria digitata at 

 low water, and they keep up a wavy series of contractions of the body. The same were 

 met with on the laminarian blades in Lochmaddy. 



The tubes vary considerably in composition according to locality, and the fimbriated 

 anterior end is not always present. Some are covered with diverse fragments of 

 bivalve shells which often have the pearly surface exposed, thus blending the lustre 

 of Nuciila and Trochus, the Avhite of the cockles, the pink of Tellina, the purple of 

 Donax, the brown and purple of mussels and other sea- worn fragments with entire 

 but minute univalves and many Foraminifera. These are mingled with pieces of gravel, 

 fragments of the spines of sea- and heart-urchins, fragments of the tests of the two 

 latter, and of Balani and Serpula^. Other tubes are mainly composed of the hyaline 

 secretion with few sand-particles, or are chiefly made up of fine grains of gravel mixed 

 with the tests of Foraminifera, whilst a third series are curiously thatched with 

 fragments of the spines of Amfliidotus mixed with minute Foraminifera and fragments 



1 ( Beobach. Anat, Entwickl./ p. 72, Taf. viii, figs. 12 and 13, Taf f ix and Taf. x, figs. 1—8. 



