Involute.] 



MOLLUSCA. 



25 



2. N. Alderi, pi. LXI, f. 1 ; Natica Alderi, Forbes, Mala- 

 cologia Monensis, p. 31, pi. 2, f. 6, 7- 



Shell nearly globular ; with the spire somewhat produced, 

 acute, consisting of five volutions, divided by a shallow suture ; 

 the lower volution largest, and rounded; the upper ones nearly 

 flat ; surface smooth, purplish-brown, with two bands of plain 

 yellow, which are each bordered by two narrow bands of white, 

 spotted with brown; lower part of the first volution white; a 

 dark brown band bounds and enters the umbilicus, which is 

 neither grooved nor striated; pillar lip brown and white, slightly 

 reflected on the umbilicus; inside brownish white; operculum 

 corneous. 



Young shells have the spire less produced, and the markings 

 paler. 



Mr. Forbes says, " this appears to be as generally distributed 

 on our shores as the last (N. monilifera), with which it has 

 hitherto been confounded. Indeed, I had for some time 

 (though not without doubts) regarded it as the young of the 

 last, until my attention was directed to its own young by that 

 eminent conchologist, Mr. Alder of Newcastle. Since then I 

 have taken the shell of all sizes, so as to leave no doubt of the 

 identity of the larger specimens with the smaller." 



3. ~N. intricata, pi. XIII, f. 13, 16 First Ed., pi. 43, f. 13, 



16; Natica intricata, Fleming, Brit. An., p. 319; Nerita intri- 

 cata, Donovan, Brit. Sh., V, pi. 167; Nerita canrena, Montagu, 

 Test. Brit., Sup., p. 149. 



Shell nearly globular, smooth, shining ; body large ; spire 

 very small, consisting of three rounded volutions; colour livid, 

 with bands of sagittate, ferruginous lines ; umbilicus large, fur- 

 nished with two divergent, spiral ridges and two grooves; aper- 

 ture subovate, sublunate ; outer lip smooth, thin at the edge ; 

 pillar lip broadly reflected on the columella. Size somewhat 

 more than half an inch. 



Found at Weymouth by Mr. Donovan, and I dredged a dead 

 shell in the Frith of Forth. 



4. N. Montagui, pi. XIII, f. 3, 6, 7, 1 1.— First Ed., pi. 43, 

 f. 3, 6 ; Natica Montagui, Forbes, Mai. Mon., p. 32 ; Natica 

 rufa, Fleming, Brit. An., p. 319; Nerita rufa, Montagu, Test. 

 Brit., Sup., p. 150. 



Shell ovate, smooth, glossy ; body large ; spire small, con- 

 sisting of four rounded volutions, separated by a deep suture, 

 terminating in an obtuse apex; aperture semi-ovate ; outer lip 

 thin at the edge ; pillar lip white, narrowly reflected on the 

 columella ; umbilicus deep, and hollowed by a spiral groove, 

 which terminates in a notch on the columella, and a rib crossing 

 half over the opening; colour livid or purplish, with a white 

 band investing the superior portion of the volutions; inside 

 yellowish orange. Length five-tenths of an inch ; diameter 

 one-eighth of an inch. 



Inhabits the Frith of Forth, in which locality a beautiful spe- 

 cimen was found by my friend Dr. Knapp of Edinburgh ; it is 

 also met with on the north coast of the Isle of Man ; but is a 

 rare species. 



5. N. glabrissima, pi. XIII, f. 9, 12 — First Ed., pi. 43, f. 

 9, 12 ; Nerita glabrissimus, Brown, Wernerian Mem., II, pt. 

 2nd, p. 532, pi. 24, f. 12. 



Shell nearly globular, pellucid, bluish-white; body large; spire 

 small, flat, consisting of three deeply divided volutions; covered 

 with rather wide, oblique, longitudinal stria; ; aperture sublu- 



nated; umbilicus long, narrow, and pointed at both extremities; 

 surface covered with fine, regular, longitudinal stria; internally ; 

 aperture semilunar ; outer lip very thin, acute at the edge ; 

 pillar lip slightly reflected on the columella. Size one-eighth 

 of an inch. 



Found in Dublin Bay, by Dr. Turton. 



6. N.pallidula, pi. XIII, f. 12, 19— First Ed., pi. 43, f. 12, 

 19; Natica pallidula, Fleming, Brit. An., p. 320; Nerita pal- 

 lidula, Donovan, Brit. Sh., I, pi. 16, f. 1, 1 ; Da Costa, Brit. 

 Sh., p. 51, pi. 4, f. 4, 5; Montagu, Test. Brit., p. 468; Brown, 

 Ency. Brit., VI, p. 462. 



Shell orbicular, subpellucid, of a light yellowish brown, or 

 horn colour; body very large; spire extremely small, consisting 

 of two, lateral, hardly produced, but well defined, volutions ; 

 aperture semilunate, very large, the external margins of the lip 

 as wide as the shell ; outer lip thin, its margin fringed by the 

 epidermis protruding from behind ; pillar lip wide, white, con- 

 cave, with an elongated umbilicus, in its centre, contracted at 

 both extremities ; inside glossy ; whole shell covered with a 

 rough, brown, epidermis, beneath which the surface is nearly 

 smooth, or faintly wrinkled, longitudinally. Length nearly half 

 an inch ; breadth three-eighths. 



Found on the coasts of Kent, Dorsetshire, and Falmouth, 

 in Cornwall ; and the Frith of Forth ; it is, however, a rare 

 species. 



7- N tuberosissima, pi. XIII, f. 18, 20 — First Ed., pi. 43, 

 f. 18, 20; Natica tuberosissima, Fleming, Brit. An., p. 320; 

 Nerita tuberosissima, Montagu, Test. Brit., Sup., p. 150, pi. 29, 

 f. 5. 



Shell orbicular; body very large; spire extremely small, con- 

 sisting of three volutions, hardly elevated above the body, on 

 which there are four elevations broken into tubercles; aperture 

 nearly circular ; pillar lip narrowly reflected on the columella ; 

 umbilicus large. Diameter somewhat more than one-eighth of 

 an inch. 



Said to have been dredged in deep water, in the Frith of 

 Forth, by Captain Laskey, a single live specimen only occurring. 

 It has much the aspect of a foreign shell. 



Genus 32 Neritoides Brown. 



Shell strong, thick, subrotund ; spire depressed ; aperture 

 nearly round ; outer lip almost continuous, having a slight 

 groove only at its junction with the body; destitute of an 

 umbilicus : operculum nearly circular, horny. 



1. N. littoralis, pi. XIII, f. 14, 15, 21, 22— First Ed., pi. 

 43, f. 14, 15, 21, 22; Nerita littoralis, Da Costa, Brit. Conch., 

 p. 50, pi. 3, f. 7, and pi. 4, f. 2, 3 ; Donovan, Brit. Sh., I, pi. 

 20, f. 2; Montagu, Test. Brit., p. 467; Fleming, Brit. An., p. 

 318; Littorina Neritoides, Forbes, Mai. Mon., p. 19. 



Shell semiovate, strong, thick ; body large ; spire small, con- 

 sisting of three or four volutions, which are placed laterally, and 

 sometimes quite depressed, and in others produced, and divided 

 by a slight suture, hardly perceptible at the apex; aperture sub- 

 orbicular, in some specimens inclining to oval, smooth, white, 

 purple, or orange within ; outer lip thin at the edge, considerably 

 thickened within ; pillar lip smooth, reflected on the columella; 

 whole shell covered by a thickish epidermis, varying in colour, 

 mostly of a drab, and frequently of an orange-yellow, red, or 



