322 trochid^e. 



according to S. Wood, in the Red and Coralline Crag. 

 It inhabits the north of France (Mace, Cailliaud, and 

 J. G. J.) ; Portugal and Spain (M f Andrew) ; Gulf of 

 Lyons (Martin); Ajaccio (Requien); Malta and Sicily 

 (M f Andrew); Algiers (Weinkauff); and M f Andrew ob- 

 tained a dwarf variety at Tunis. Its range of depth in 

 the Mediterranean is from 12 to 50 f. 



When placed on its back, with the shell underneath, 

 it twists about actively, in order to regain a footing. 

 The edges of the foot in this and other species of Trochus 

 are occasionally folded inwards and brought together, 

 so as entirely to conceal the disk or sole. I put a live 

 specimen of T. Montacuti into fresh water for three 

 minutes ; it withdrew into the shell, and by keeping its 

 door shut suffered no inconvenience, as soon appeared 

 upon its being restored to its native element. The spiral 

 ridges in the fry are frequently marked with reddish- 

 brown lines. 



This species is the T. Cyrnceus of Requien, and 

 Montagua Danmoniensis of Leach. 



11. T. stria'tus"*, Linne. 



T. striatus, Linn. S. N. p. 1230 ? ; F. & H. ii. p. 508, pi: lxvi. f. 5, 6. 



Shell proportionally narrow at the base, more or less flat- 

 tened on the underside, with a rather sharply keeled periphery, 

 solid, opaque, and somewhat glossy : sculpture, fine spiral ridges, 

 of which there are eight or nine on the last and next two 

 whorls, the number decreasing towards the apex ; the lowest 

 ridge is the largest, and forms the basal keel ; there are also 

 from ten to twelve similar ridges on the base ; the whole sur- 

 face is covered with delicate and numerous imbricated striae, 

 which obliquely cross the ridges, but are stronger in their 

 interstices ; sometimes the ridges are partly nodulous in con- 

 sequence of this decussation: colour pale yellowish, or white 

 with oblique streaks of dull red or very dark brown (nearly 



* Striated or grooved. 



