NOTE ON MITRA STEPHANUCHA, MELV., WITH 

 DESCRIPTION OF A PROPOSED NEW VARIETY. 



r.v JAMKS COSMO MELVILL, M.A,, F.L.S. 

 (Plalc viii, figs. 16, 17.) 



Since December 1S96, wlu-n the first e\aai])les of this fine mollusc 

 were described, it has been been frequently dredged, and is now fairly gener- 

 ally to be found in collections. 



The largest specimen we have seen, now figured, came from the neigh- 

 bourhood of Muscat, in 1901 (this being the original and central habitat for 

 the species), and measures longitudinally 45 as against 42 millimetres in the 

 type This individual is of a warm and cinereous-brown. The whorls are 

 at least 15 in number, the actual apex not being cjuite perfect, while the 

 spiral row of strong echinukite coronals in the upper part of the longitudinal 

 ribs is extremely well develojjed. Below these, only traces of the usual 

 transverse interrui)ted dark line, so c()ns])icu()us as a rule, exist, and 

 this is followed b\- a plain grev and somewhat indistinct spiral band. 



As a contrast to this, a remarkable form has been (juite recently dredged 

 in the locality given below, and as it possesses so many points of similarity 

 to M. sfcjihnnufha it is the wisest course to deeiii it a marked variety, at 

 all events till more specimens come to hand. 



I therefore characterise it thus : 



Mitra (Costellaria) stephanucha. Mti^. 

 var. astephana, "-' nov. 



Shell in general form and coloration as in the type, but much smaller, 

 II — 12 whorled, perhaps not (juite full grown, the 2.^ apical, glassy jjale 

 brown, the rest longitudinally ribbed, ribs shining, smooth, number on the 

 body whorl 13 as against 10 — 11 in the normal f(jrm, when mature, u[)per 

 whorls interstitially spirally punctately sulcate, less deeply, but still consi^ic- 

 uously on the lower whorls, there being a grey central zone at the centre of 

 the basal, as in the t)[)e, with interrupted s[)iral dark line, between the ribs on 

 the five last whorls. 'I'hc echinate and acutely-noduled coronal, on the 

 other hand, round the upper portion of the ribs is Wi-U nigh or quite obsolete, 

 giving a perfectly different character tf) the f.ieies of this nt'W \aricty, pro- 

 posed from this circumstance, to be called (i.<frj>Iiiii/(i. Indeed, it seems- 

 comparable with such a s[jecies as .1/ ( Cosfi^/htn'a) no'lil ijrdtd, A. Ad from 

 the Philippines. I would adil, that Messrs. Sowerby & Fulton, in their last 

 issued elaborate catalogue of Mollusca (April, 1903, p. 18) elassity M. 

 ^feplmnurha as a Callifhrui, in which subgenus .1/, xfiijinniiu-in and miKjui^uiia 

 are placed The variety just described certainly bears a relationshi|i lo these 

 latter, and wl- are nf)t sure diat Callitlifa does not therefore suit thi: specie. 

 better than Cosfpllaria : but the two sul)-di\ isions run very closeh' togetlier, 

 and are not well defined. 



Long 20, lat. 6.50 millim. 



Hah. — r.ulf of Oman. Lat 26° 6' N„ long. 56° 53' E., 15 fathoms. 



12. ' LoTecfiavoS, without a coronal. 



