400 GASTROPODA. [Pectinibranchia. 



Subgen. 1. MURICAXTHA, Swainson, 1840 (em.). 



Muricanthus, Swains., Treat. Malacology, 1840, 296. Type : Murc.r radix, 

 Gmelin. Centronotus Swains., 1835; not of Schneider, 1801. Phyllonotua. 

 Swains., 1840. Bassia, Jouss., 1879 ; not of Quoy and Gaimard, 1834. 



Shell broadly ovate, with from 4 to 15 scaly or foliated varices ; 

 whorls rounded, spiral sculpture well developed ; spire ranging from 

 depressed to considerably elevated ; canal of moderate length, curved, 

 nearly closed ; aperture ovate ; outer lip crenulated. 



Sect. 1. MURICANTHA, S. Stl'. 



1. Murex octogonus, Quoy and Gaimard, 1833. Plate 48, tig. 1. 



Hurex octoijonus, (). & G., Voy. Astrol., ii, 1833, 531. pi. 36, f. 8, 9. Gray, 

 in Dieff. N.Z., 229 ; Button, M.N.Z.M., 47 ; T.N.Z.I., xvi, 218 ; Tryon, 

 Man. Conch., ii, 110, pi. 30, f. 272-73 ; Conch. Icon., iii, pi. 29. f. 'l34. 



Shell ovato-fusiforrn, narrowly perforated, solid, with spiny varices, 

 brown. Sculpture : The first four whorls below the protoconch axially 

 costate, the number of costse varying from 8 to 10 ; further down 

 they are forming strong varices, each carrying hollow spines, which 

 are recurved and open on the anterior side ; those on the carina of 

 the whorls are usually much longer than the others ; their number is 

 4 on the antepenultimate, 7 to 8 on the penultimate, and 11 to 13 on 

 the body-whorl ; they extend over the base to the middle of the canal ; 

 around the umbilical fissure there is a half-circle of former canals, 

 each of them being the continuation of a varix, and their number 

 varies from 4 to 5. The spiral sculpture consists of narrow rounded 

 ribs of subequal strength, narrow or subobsolete upon the shoulder of 

 the whorls, sometimes with a fine thread in the interstices ; they are 

 usually scabrous between the varices, on which they are produced 

 into spines. Colour varying from cinereous to dark brown, the spiral 

 lirse mostly of darker colour ; interior of the aperture white, often 

 tinted with purple or light brown. Epidermis thin, persistent, not- 

 shining. Spire conical, gradate, with a sharp apex, about 1^ times the 

 height of the aperture without the canal. Protoconch very small, of 

 1| smooth whorls, convex, the nucleus lateral. Whorls 9 to 10, first 

 slowly then more rapidly increasing, distinctly shouldered, flattish 

 on the shoulder, lightly convex below it ; base contracted. Suture 

 not much impressed, wavy. Aperture ovate, rounded above, pro- 

 duced below into a moderately long recurved canal, which is only very 

 narrowly open, and rounded at its base. Outer lip angled above, thin 

 and sharp, deeply grooved. Columella short, subvertical, lightly ex- 

 cavated and obliquely truncated below. Inner lip forming a fairly 

 thick callous layer over the columella and upon the concave parietal 

 wall, usually extending a little beyond the pillar, often terminating 

 in a free sharp edge. Umbilical fissure narrow, but distinct. Oper- 

 culum solid, horny, light brown, with a subapical nucleus. 



