| OCR Text |
Show 1882.] MOLLUSCAN FAUNA OF MADAGASCAR. 385 deposit of callus, before the deposition of which the starting-point of the columella is conspicuously defined by a transverse white line, which starts just above the umbilicus and winds round the penultimate whorl within the aperture. Operculum generally dirty lilac on the inside, but sometimes white or horny-brown. Height 50 millim.; greatest diam. 49, smallest 38 ; aperture 36 long, 23 wide. Hab. In a marsh, north of Antananarivo (Johnson) ; Imerina province (Cowan). In form this species is not unlike A. largillierti of Philippi, but it is quite distinct in several respects. The spiral striation is finer, the umbilicus broader ; the aperture is not angular or effuse at the base, nor has the last whorl the rounded keel or ridge at the base around the umbilical fissure. A. cecillei, Phil., appears to be more ovate, with less tabulated whorls, has a higher spire, and is differently coloured. It is only in adult specimens that the commencement of the aperture near the lip is yellow. The columella is also of that colour in full-grown shells, but bluish white in young ones. This species appears to arrive at maturity after two years' growth, as all the large specimens exhibit a dark longitudinal stripe or former lip just before the completion of the fifth whorl. In the young state this is very thin, and the colour is horny-brown, and not greenish olive like the last large whorl of the adult. LIMN^EA HOVARUM, Tristram. Limnaa hovarum, Tristram, Proc. Zool. Soc. 1863, p. 61. Hab. Ankafana, Betsileo (Cowan). This species grows to a larger size than that of the specimen described by Tristram; tor one from the above locality is as much as ten lines long. In the larger shells the lines of growth become more prominent, forming arcuate and tortuous elevated ridges. The columella also is reflexed, appressed to the whorl, yet leaves a slight chink or rimation in the umbilical region. All the specimens examined exhibit traces of transverse or spiral striae, generally interrupted and of a subpunctate character. LIMNAA ELECTA, sp. nov. (Plate XXII. figs. 12, 13.) Shell small, ovate, transparent, corneous, narrowly rimate. Whorls 3_3± convex, rapidly increasing. Spire small, obtuse and reddish at the apex. Last whorl elongate, sculptured with fine lines of growth crossed by a few spiral striae. Aperture vertical, ovate, acuminate above, occupying about two thirds of the entire length of the shell. Columella rather high up, reflexed over the umbilical fissure, the reflexed portion being striated rather coarsely lengthwise. Length 6| millim., diam. 4 ; aperture 4| long, 2 | wide. Hab. About 20 miles from Antananarivo (Johnson). This little species has much of the general aspect of the genus Succinea, and is peculiar on that account and the red tip of the spire. |
