GASTROPODA. [Aspidobranchia. 



KEY TO SPECIES. 



A. Shell without spots, colour mostly bluish-black, outer lip not or 



very narrowly black-margined within . . . . . . nigerrima 



B. Shell with or without yellow spots, colour purplish-black, outer 



lip conspicuously black-margined within . . . . coracina. 



1. Monodonta coracina, Troschel, 1851. Plate 38, fig. 4. 



Trochus cm-acinus, Troschel, in Philippi, Condi. Cab., 1851, 148, pi. 24, 

 f. 13; Fischer, Coq. Viv., 357. pi. 110, f. 6. Monodonta 'coracina, 

 Trosch., Man. Conch. (1), xi, 103, pi. 19, f. 94; pi. 31, f. 28: Suter, 

 P. Mai. S., ii, 264. Labio porcifera, A. Adams, P.Z.S., 1851 (1853), 179, 

 not of Watson. Diloma nigerrima, Chemnitz : Hutton. M.1ST.Z.M 96 - 

 P.L.S. N.S.W., ix, 366, not of Chemnitz nor Gmelin. 



Shell small, imperf orate, orbicular-conoid, depressed, solid, lustre- 

 less. Sculpture : Kather distant spiral liree, sometimes obsolete, 

 crossed by oblique growth-lines. Colour purplish-black or black^ 

 \micoloured, or sparsely dotted, especially on the base, with yellow. 

 Epidermis solid, not easily eroded. Spire low and arched, or conical 

 with rounded apex. Protoconch of 2 flatly convex whorls, which are 

 finely spirally lirate with very distinct oblique growth-lines. Whorls 

 4 to 5, slightly convex, the last large, concave below the suture, ob- 

 tusely angulate at the periphery, eroded in front of the aperture ; 

 base flatly convex. Suture linear, margined below by a low and 

 rather broad pad. Aperture very oblique, reddish iridescent and 

 lirate. Outer lip convex, sharp, black-edged inside, followed by a 

 white opaque band which continues as a pearly stripe over the 

 umbilical tract, parallel to the columella, and connects the termi- 

 nations of the peristome. Umbilical tract bounded on the outer lower 

 margin by green, grey, or brown. Operculum round, light brown, 

 horny, multispiral ; nucleus central. 



Diameter, 8-5-10 mm. ; height, 6-9 mm. Diameter, 17 mm. ; 

 height, 19 mm. (specimen from Kawhia). 



Dentition. Suter, P. Mai. S., ii, 265, fig. in text. 



Type (?). 



Hab. Coast near Kawhia (H. S.) ; Wellington Harbour (H. S.) ; 

 Lyttelton Harbour (H. S.) ; Sumner, near Christchurch (H. S.) ; Pre- 

 servation Inlet ; Chatham Islands ; Auckland Islands (Captain 

 Hutton). 



Remark. This is the most variable species of the genus. 



2. Monodonta nigerrima, Gmelin, 1790. Plate 38, figs. 5, 5a. 



Turbo nigerrimus, Gmel., Syst. Nat., ed. xiii, 3597 : not Trochus nigerrimus, 

 Gmel., a species of Chlorostoma. Diloma nigerrima. Ad., G.R.M., iii, 

 pi. 47, f. 7, 7c ; Chenu, Man. i, 358, f. 2658. Monodonta nigerrima', 

 Gmel., Man. Conch. (1), xi. 97, pi. 23, f. 77, 78 ; pi. 20. f. 18. Trochus 

 araucanus, d'Orbigny, Voy. Amer. Merid., Moll., 410, pi. 55, f. 6. 

 Turbo Quoyi, Kiener, Spec, et Icon. (Turbo), pi. 29, f. 2 ; not Trochus 

 Quoyi, Phil. Monodonta porcifera, Watson: Suter, P. Mai. S., ii, 264, 

 not of Adams nor of Watson. Trochus Gaiidichaudi. Hupe, in Gay' 

 Hist. fis. Chile, Zool., viii, 1854, 146, pi. 4, f. 4. 



