邦産ツノヲリイレ類の2新種

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Boreotrophon stephanos, nov. sp. Figs. 1, 4. Shell large, creamy white on the surface; whorls highly elevated, 7 in number exclusive of nucleus; subsequent whorls with 7 or 8 erected, broad, lamellar varices, prolonged upward at the shoulder so as to form prominent, recurved spines, which are hollow on one side, roundly ridged on the other, with broad interspaces crossed with feeble, irregular spiral striae, 6 to 10 on the body whorl; shoulder vaulted, not angulated; behind the shoulder the whorl roundly arched; base of the whorl well constricted; canal long, open, slightly recurved, inbricated with the remnants of old canal ends on the siphonal fasciole, with deep umbilical chink; aperture oval, creamy yellow within, tinted with light brown on the throat; peristome broadly reflected outside. Height of shell 59 mm, maximum diameter 25 mm, excluding varices, aperture and canal 37 mm in length. Operculum oval in shape, thin, horny, with distinct concentric striations and terminal nucleus, 14.5 mm in length, 8.5 mm in maximum width. This species belongs to the group of American B. stuarti, but differs from the typical form in having the much longer spire and canal, the rounded shoulder, more numerous and feebler spiral striae on the body whorl and the oval shaped aperture. From B. smithi it differs by more rounded shoulder, the less constricted suture, the much longer spire and canal, the oval shaped aperture, the presence of feeble spiral striae on the whorl, the less recurved canal, being much larger in size, and from B. peregrinus in having much longer spire and canal, the rounded shoulder, the oval shaped aperture, the smaller number of spiral striae. Another related form, B. multicostatus, has a more angular shoulder, with no varical spines above the whorl and the shorter spire and canal. The dinstinguishing characteristics of these species are shown in Table 1. Loc. Honto, Karahuto. Boreotrophon alborostratus, nov. sp. Figs. 2, 3, 5-8. Shell thick, solid, pure white; nucleus eroded, 6 subsequent whorls weekly angulated at the periphery, bearing 11-13 narrow, appressed varices, which are only prominent at the shoulder as the short, erected, blunt spines; whorls ornamented with numerous, fine spiral striae, but when eroded with sagrinate sculpture on the surface, strikingly constricted at the base; spire elevated; suture distinct, but not deeply grooved; canal long, slender, straight widely open, imbricated with old ends on the siphonal fasciole, without umbilical chink; aperture oval in outline, pure white, polished, shining; pillar also polished, shining; outer lip slightly patulous opposite the base of the pillar; opereulum horny, dark brown, with terminal nucleus, attaching surface narrow, clescentic in outline. Body yellowish, maculated with irregular, small, black patches on the whole external surface; proboscis sheath (fig. 8. ps) short; proboscis (pr) remarkably long; foot (ft) with deep pedal groove at the anterior margin; buccal mass (bm) small, elongate fusiform; pharynx (ph) very slender; stomach (st) fiddle-shaped, opening into the mid-gut together with the liver at the initial portion of the gut; thick walled mid-gut (mg) consisting of 5 small diverticula; rectum (rt) simple, opening near the mantle edge, together with the renal opening; osphradium (os) elongate oval shape, dark green in colour; kidney (kd) large, lying under the rectum near the heart (vt, au); salivary gland (sg) very large, situated on each side of the cephalic ganglion, with very long strongly winding duct (sd), directed to the buccal mass along the pharynx; central tooth of radula (fig. 6) with 3 cusps of subequal length; lateral tooth bicuspidate, outer cusp larger, slightly recurved near the tip, inner cusp a little curved, acute at the tip. This species belongs to the same group as B. alaskanus, though differs from it in having more numerous varices, much more procumbent, shorter spines at the shoulder, the strikingly constricted base, lo
社団法人日本動物学会の論文
1938-09-15

邦産ツノヲリイレ類の2新種

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