NICOLEA. 149 



convex base. Several striae pass obliquely from the upper teeth to the posterior border. 

 The posterior hooks are somewhat less and the curves of the posterior outline and base 

 slightly vary. The foregoing hooks differ from those of the Mediterranean species, which 

 have a process on the edge of the base beneath the main fang (Plate CXX VI, fig. 1 6), and 

 the curvatures also differ. If this form represents Savigny's L. medusae then the British 

 species should be called L. Montagui. 



The tube of Loimia medusae, Sav., is comparatively short, composed of grains of sand 

 and fragments of shells. Gravier found the longest to be 15 cm., and the diameter 

 8 — 9 mm. The tube of the British species is probably similar. 



Most of the older authors, such as De Blainville, 1 refer to Savigny's species. It is 

 doubtful if Montagu's Terebella constrictor refers to the present form, yet this careful 

 observer could scarcely have overlooked so fine a southern species as the present. 



C. Gravier 2 describes interesting variations in the young examples of Loimia 

 medusae, Sav., in which the first and second segments differ, and the third has a lobe which 

 disappears in the adult, the branchiae are less finely ramose at the tip, and the hooks, 

 instead of having the teeth on the crown in a single row, have them double. It is 

 possible, however, that there may be allied forms which show these distinctions, for even 

 in Arenicola, to which the able French author alludes, friction will account for many 

 of the changes between the hooks of the young and those of the old. 



Genus CXLVIL — Nioolea, Malmgren, 1865. 



Sclone and Axlonlce, Malmgren; Phy sella and Heterophil sella, De Quatrefages. 



Cephalic collar small, with a row of distinct eyes behind it, the anterior border 

 forming a spout-shaped arch over the mouth. Body typical. Branchiae two, attached 

 to the second and third segments, the anterior being the larger, dichotomously divided 

 with short terminal branches. Sometimes a third pair of branchiae. Fifteen to seventeen 

 setigerous processes, the first behind the second gill on the fourth segment ; the bristles 

 have narrow wings on the long and finely tapered tips; no shorter series occurs in 

 the tufts. A short cirrus in males over the fascicles of bristles in. the third and fourth 

 segments : none in females. 3 The avicular hooks commence on the second setigerous 

 segment, (fifth) uniserial at first, then at seventh biserial for seven segments, afterwards 

 uniserial. Ventral scutes conspicuous. The anterior nephridia are a little less than 

 the posterior. Tubicolar. 



1 ' Diet. Sc. Nat. Vers, et Zooph./ pi. v, fig. 1. 



2 f Nouv. Arch. Mus. Paris/ 4 e ser., t. viii, p. 224, with text-figs. 396 — 399. 



3 A rather thick cirrus over the bristles of the fourth and fifth segments occurs in N. zostericola 

 and N. venustula from Plymouth, so that there is no difference in this respect. The processes were 

 larger in the small N. zostericola than in the adult N. venustula. Allen says Crawshay gives 

 N. venustula seventeen pairs of bristle-tufts, whereas in N. zostericola there are fifteen. Fauvel gives 

 N. venustula fifteen to seventeen pairs of bristles and states that the two forms belong to one species. 

 Tauber found three pairs of branchiae and sixteen to seventeen bristle-tufts in N. zostericola and 

 Leuckart, in this form, describes three pairs of branchiae and fifteen bristle-tufts. 



