138 SPIONIDS. 



more. The head was devoid of tentacles, and had four touches of pigment disposed in a 

 trapezium and without lenses, whilst each segment had a yellowish-brown stellate 

 pigment-speck. They may be compared with the form alluded to on p. 152. 



The cilia in the Spionids generally occur in two rows on the dorsum, between the 

 branchiae, which also bear a conspicuous one, though in some cases only a single row 

 occurs on the dorsum (Lubischew). 1 



R. Leuckart describes and figures a larval Spionid with a pointed snout and the pro- 

 visional spiny bristles, from Nice and Villafranca, and in which the alimentary canal is 

 pinnate throughout the greater part of its length, as in Pxcilochxtiis. The snout 

 resembles that of Nerine cirratulus. 



The pelagic larvae (Plate XCIV, figs. 8 — 11 and 14) pertaining to this family (e.g. 

 Polydora) occur in the tow-nets from January onward, though they are fewer in that 

 month than in February. Nerine appears about the same time, and swarms in April. 

 Young Magelona occurs in May and also in June, July, and August, when larvae of 

 Spionids are very abundant. Such forms as Magelona appear to have passed their larval 

 stages and to have entered the later stages before they take up their residence on the 

 bottom, since they still are captured in the nets in August. The bottom-nets in Sep- 

 tember teemed with numerous Spionids, amongst which were the young of Magelona with 

 the papillae well-developed on the tentacles ; whilst in the surface-nets of the first half of 

 October they still were present, though in limited numbers, and the same may be said of 

 November. 



Reproduction of lost parts readily takes place in the Spionidae, the facility with 

 which many rupture their bodies being thus compensated by readiness in reproduction. 

 Amongst others, Bobretzky 2 observed reproduction of the anterior region in Spio Ixvi- 

 comis, and Jacobi 3 in Polydora quadrilobata. Mesnil 4 also records the same in Polydora 

 Giardi, P. armata, Nerine cirratulus, and Pygospio elegans. Nusbaum 5 and Ivanow 

 observed this feature in Nerine cirratulus, whilst Giard 6 found that larvae of Polydora 

 regenerated either end. 



Spionids frequent clean sand along the margin of low water and some distance shore- 

 wards, as well as range to deep water, even the common Nerine foliosa descending to a 

 depth of 725 fathoms. Many form protective tubes of secretion and sand, whilst others, 

 like Polydora, penetrate shells and rocks of various kinds, and in regard to wide distribu- 

 tion and the general effects of rock and shell erosion the family is one of the most con- 

 spicuous. Their colours are often bright, browns, greens, and yellows predominate, 

 whilst in many the crimson vessels in the branchiae enliven the other shades. Their 

 distribution is wide, but many are confined to shallow water. Thus, in the 'Challenger,' 

 only the genera Scolicolepis (S. cirrata) and Prionospio occurred. 



1 'Mitt. Zool. Stat. Neap./ Bd. xx, p. 348, 1912. 

 ' Mem. Soc. de Natural, de Kiew/ t. i, 1870. 

 'Inaug. Dissert./ Taf . ii, 1883. 

 1 Bull. Sc. Fr. et Belg./ t. xxix, pi. vii— xv, 1896. 

 ' Zeitschr. f. wiss. Zool./ Bd. lxxix, Taf. xiii— xvi, 1905. 

 c C. R. Assoc. Francaise/ 1901, pt. 1, p. 153. 



