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Show 1873.] MR. R. B. WATSON ON MADEIRAN MOLLUSKS. 375 Mr. Gwyn Jeffreys says of it, " certainly a new species, but closely allied to R. watsoni;" and he adds that it resembles also R. tenera of Philippi. I have called it after m y friend, that excellent island-naturalist Senhor Joao Maria Moniz. RISSOA WATSONI (Schwartz). (Plate XXXV. fig. 11.) Shell conic-oblong, thin, transparent, rather brilliant, glossy; whorls rising somewhat in steps. Sculpture. Spiral threads on body-whorl 9-10, prominent, rounded; first generally smaller than others ; the second forms a kind of shoulder, and along with third and fourth is usually somewhat more prominent than the rest; the last winds close round the pillar. On the fourth whorl there are four of these threads ; on the third and lower part of second whorl three. In second whorl these threads are abruptly cut off, and are replaced in embryonic shell by about eight non-transparent spiral furrows, parted by fretted ridges y-gVo inch broad. The interstices of the spiral threads are from two to three times the breadth of the threads, the three higher threads being somewhat wider apart than the others. In these interstices the surface is covered with microscopic spiral scratches, which, however, are neither sharp nor deep enough to interfere with the general glossiness of the shell. Very often these interstices are crossed longitudinally at unequal intervals by 20 to 25 faint ribs (sometimes no more than lines), which do not at all show upon the threads, and which die away at the periphery. The labial rib is somewhat remote from the lip, is rather broad, and is very little raised. Colour generally yellowish white, flecked along the spiral threads and also (near the suture) in the interstices with opaque white and brilliant ruddy brown patches, often passing over from this into uniform dull white or rich brown. The extreme apex never has a blackish tip. Spire long, ending in a perfectly hemispherical top, of which the embryonic tip generally forms the very apex. Whorls 4|, not so much rounded as angulated by a sloping shoulder below the suture, most strongly marked on left side of shell; of regular increase. Suture very strongly marked, but shallow, somewhat oblique. Mouth very well rounded, its curve being only a little contracted across the body, very slightly expanded at lower inner corner. Lip sharp and thin, scarce marked on outside by the spiral threads. Inner lip very sharp, and so far reflected and projecting as it advances downwards as almost wholly to conceal the pillar, leaving a slight umbilical chink behind it. It is thinly continued across the body-whorl to meet the upper corner of the outer lip. Sh. M. 5. 4. 3. 2. 1. L *066 *027 '028 *017 *01 *007 *004 B *038 -025 *027 *035 *025 *016 *008 |