OCR Text |
Show 298 MR. E. A. SMITH ON THE [Apr. 1, A C T I O N SEMISCULPTUS. (Plate XXIV. fig. 8.) Testa ovata, turritu, parva, nitida, nivea, angustissime rimata, superne Icevis, infra medium subdistanter transversim punctato-striata ad basim coufertius striata, sidcis paucis longitudinalibus indistinctis, crenatis, distantibm sculpta; anfractus quatuor, leviter convexi, sutura anguste canaliculata sejuncti ; apex invo-lutus ; apertura inverse auriformis, longit. totius ^ jpaullo superans ; columella anguste reflexa, plica p>arva prope rimam munita. Longit. 4 millim., diam. 2\. The spiral transverse punctured striae do not extend above the middle of the body-whorl. The longitudinal narrow aud shallow indistinct sulci apparently indicate lines of growth. LEUCOTINA MINUTA. (Plate XXIV. fig. 9-) Testa minuta, oblonga, alba ; aufractas 5, primus {nucleus) rotuu-datus, introversus, spiraliter liratus, cceteri convexi, liris spiralibus (in anfr.penult, circiter 7) instruction interstitiis, liris paulo angustioribus, lineis longitudinalibus tenuissimis sculpti ; apertura ovata, superne acuminata, inferne cum columella arcuata et dilatata leviter effusa ; plica columellce centralis, distincta. Longit. 2\ millim., diam. f. Var. brevior 2 | longa, 1 lata. The apex of this interesting species is peculiar, being introverted as it were, and partly enveloped by the succeeding whorl. It is not smooth, as is frequently the case in other species, but obliquely spirally lirate. The raised lines in the grooves between the ridges produce a subpunctate appearance. The genera Myonia and Leucotina were described by A. Adams in tbe 'Annals and Magazine of Natural History,' 1860, vol. v. p. 406. On examining the diagnoses a great similarity is observable, and, indeed, with the exception of a slight difference in form, there seems to be very little, if any, distinction. I therefore would propose that these genera be united, in which case Leucotina may be retained, Myonia being preoccupied. M. japonica, A. Adams, I have not seen ; but Actceon modesta, A. Adams, Monoptygmct casta = 31. concinna, both of A. Adams, and Daphnella casta, Hinds, all typical forms of Myonia, have been examined, and they do not offer any characters which will separate them generically from Leucotina niphonensis, A. Adams, L. diatice, A. Adams (described as an Actceon), &c. One of the species of this genus, L. casta, A. Adams, has been referred by Watson (' Challenger' Report of Gasteropoda, p. 487) to the section Partheuia oi Odostomia ; but this location is not correct, I think-Parthenia1, comprising longitudinally-ribbed shells, being apparently synonymous with Chemnitzia, d'Orbigny, or Turbonilla, Risso, 1826. Judging from the shell-characters, I should 1 This name was proposed by Lowe in 1840. It had previously (1830) been used by Robineau-Desvoidy for a genus of Insects. |