Report on the zoological collections made in the Indo-Pacific Ocean ...

MOLLUSC A. 396. Pleurotoma (Glyphostoma) spurca. (Plate IV. figs. F-F 1.)Clavatula spurca, Himh, Voy, ' Sulphur,'' p. 17, pi. 5. fig. 14 ; Reeve,Conch. Icon. fig. 312.Pleurotoma rava, JReeve (non Hinds), Conch. Icon. fig. 250.Hab. Port Molle, Arafura Sea, N. Australia, 32-36 fms., andPort Darwin, N.W. Australia ( Coppinger).This interesting species is subject to considerable variation bothin form and sculpture, but is nevertheless generally very easilyrecognized by the transverse plaits on the columella and the largedeep and laterally directed sinus near the upper end of the muchthickened labrum, which is armed within with five or six denticlesor short limp not reaching the crenulated edge. The basal canal iscontracted and a little recurved. The type has ten costoe upon thelast whorl, but this number is sometimes exceeded by two more.The principal lirse are normalljr two in number upon the uppervolutions, one being at the middle, the other below, nodulous uponthe costse. Above these, occupying the upper part of the whorls,are a few uninterrupted thread-like lira3, about four upon thepenultimate and antepenultimate whorls. The body-whorl hasabout fifteen principal spiral lirse, two of which pass above theextremity of the outer lip. Some varieties have three or even foursubequal principal lirte on the lower half of the upper whorls, andtwenty to twenty-four upon the last, but all agree in having thefiner lines above, which also at times exceed the typical number.The largest specimen considerably exceeds the dimensions of Hinds'stype. It is ] 8 millim. in length and 6 in width, measuring abovethe aperture, which is 8 long. Another smaller example is remarkablefor the shortness of the mouth : it is 12 long, 4 broad,with an aperture 4| in length.7. Pleurotoma ( ?) gracilenta, var.Pleurotoma gTacilenta, Reeve, Conch. Icon. fig. 114.Var. = PI. contracta, Reeve, I. c. fig. 116.Var. = PI. fusoides, Reeve, I. c. fig. 349.Hah. Arafura Sea, N". Australia, 32-36 fms. ; bottom—sand, mud,and shells {Coppinrjer); Philippine Islands (Cuminr/).This species does not conveniently fall into any of the recognizedgroups of Pleurotomidaj. In form it resembles some species ofDajyJmelJa, but has not the minutely reticulated nuclear whorls ofthat section, and the labral notch is hardly at, but a trifle below, thesuture. I fail to perceive any sufficient characters to separatespecifically the three so-called species described by Keeve ; indeedPI. co)itracta and PL fnsoides are all but identical. The type ofP. gracilenta is a trifle more attenuated than the other two, butscarcely differs in any other respect. All are longitudinally costateand spirally Urate, the costiB numbering about twelve on a whorl,attenuated above at the suture, and becoming obsolete upon thebody-volution towards the narrowed anterior end ; the principal