OCR Text |
Show 730 MR. E. A. SMITH ON NEW SHELLS FROM [June 18, apex, olive-brown, more or less coated with a black earthy deposit. Whorls probably about 9 in number, the remaining four or five slightly convex, spirally sulcate, and longitudinally sculptured with coarsish flexuous lines of growth; ridges between the sulci about 10 in the penultimate whorl and 18 in the last, those near the base separated by wider sulci than above. Aperture oval, acuminate superiorly and very slightly effuse at the base, occupying about -^ of the supposed entire length of the shell, sordid bluish within; lip very thin, broadly sinuated above and somewhat prominent below the middle. Columella whitish, moderately arcuate. Supposed total length 23 millim.; actual length of five remaining whorls 19, diameter 7^; aperture 7\- long, 4+ wide. Hub. Formosa (Dickson). This species resembles M. dolorosa, Gould, to some extent; however, it u distinguishable on account of more elongated whorls and coarser spiral sulci. Some of the lines of growth here and there are well marked, and give the whorls a subplicated appearance. BULLIA PERSICA. (Plate XLVI. fig. 11.) Shell ovate-acuminate superiorly, greyish or lavender-colour, whitish at the upper part of the whorls, with the callous band at their base white, bordered below by a brown line at the suture; and the base or cauda of the last whorl is also white. Whorls 6, the first two smooth, convex, the rest spirally sulcated, the ridges between the sulci 8 in number in the upper whorls and about 16 in the last, whereof 12 are above and 4 below the acute ridge or keel, which winds round the lower portion of the whorl. Of these ridges the four immediately below the suture are more or less white, granulous through being crossed by oblique sulci, which only extend from the suture a short distance. Aperture deep brown within, with a paler or white border at the outer lip and over the basal sinus, and a little longer than the spire. Columella moderately arched, and coated with a thinnish white enamel. Basal sinus rather broad and deep. Length 24 millim., diameter 10; aperture 12 long, 7 broad. Hab. Bushire, Persian Gulf. Two specimens of this very interesting species have recently been presented to the Museum by Mr. A. S. Betts. The peculiar form and colouring, the granular ridges at the upper part of the whorl, and the brown aperture with the white margin to the labrum and basal sinus are the most obvious distinguishing characters of the species. OSTREA, sp., adhering to Trochus (Polydonta) maculatus, Linn. (Plate XLVI. fig. 12.) This is a remarkable instance in which a shell has assumed, to a certain extent, the sculpture of another to which it has adhered. This assumption or mimicry of the surface of other shells and foreign substances has already been noticed in other species of Ostrea and other genera, and is common to most forms of the genus Myochama. The same process which effects so remarkable a change in the normal |