1890.] ON THE MitRINE MOLLUSCA OF ST. HELENA. 247 produce darker cross bands very indistinctly perceptible in certain lights. Total length 50 inches ; depth of the body behind the head \^ inch ; depth of the body in the middle of the length 1| inch ; depth of the body above the vent 7 lines ; length of the head without process 3 inches ; length of the head with the process 5 incites 3 lines ; diameter of the eye 9 lines ; length of the pectoral 10 lines ; length of one of the longest dorsal ravs 1 inch 6 lines. The first figure (Plate XIX.) represents the entire fish, much reduced, with the first dorsal ray restored to its supposed original length and form ; the second figure (Plate XX.) the head of the natural size. 3. Report on the Marine Molluscan Fauna of the Island of St. Helena. By Edgar A. Smith. [Eeceived March 14, 1890.] (Plates XXI.-XXIV.) The materials which form the basis of this Report consist mainly of a very extensive series of shells, about 2.500 in number, collected at St. Hielena by Cai)t. W. H. Turton, R.E., during the years 1884-6, and which he subsequently most liberally presented to the British Museum. A series of small shells, presented to the Museum in 1857 by E. W. Alexander, Esq., has also been worked through. A few specimens dredged by Dr. Wallich about the year 1857, others re-ceived from Sir George Grey in 1841, a small collection from the Museum of Economic Geology in 1860, and, finally, a set of the specimens collected by Mr. J. C. Melliss and enumerated in his book on St. Helena, have been examined. The greatest praise is due to Capt. Turton for the excellent manner in which the collection was made and put up for transmission to this country ; and the amount of time and labour bestowed upon it must have been very considerable. The majority of the species are very small and were obtained '* by sifting the sand and shingle which is found in a few places on the coast," and by dredging in depths up to about 80 fathoms, chiefly, but not exclusively, off the north of the island. A few were picked out of a hard kind of conglomerate of shells and sand, about four feet above high-water mark, in a bay on the north coast. This conglomerate is found in the crevices of rocks which have fallen down from the high cliffs above, quite recently, and probably it got washed up into that position by some high tide, such as occurs there every few years. Some of the specimens were found on pieces of a substance, locally called " Sea-horn" '^y which is sometimes ^ Doubtless lliese pieces of " Sea-horn " are portions of a large species of Tangle, probably Echlnnia hucchialis, which is verv thick and horny, aucl oci-nrs at tile Cape of Good Hope, whence these I'ragments had drifted.