apertural margin造句

• The apertural margin can be thick.
• The apertural margin is U-shaped with a pronounced circular angular sinus and a strong angularis.
• Growth lines are strongly bent backward on this belt, indicating the presence of a deep sinus on the apertural margin.
• These ribs function as a diffraction grating, giving the yellow shell a silky appearance . The apertural margin is simple and breaks easily.
• There are 7-8 slightly convex whorls . The apertural margin is white and usually with a white layer at the parietal side.
• In this specimen the apertural margin is irregularly broken, indicating that the teleoconch might even have more than one calcified teleoconch whorl in complete specimens.
• The apertural margin is reflected and white, not connected by a callus or white layer at the parietal side . The shell colour is evenly brown.
• On the post-larval shell a vague spiral ornament is present and the peripheral belt remains visible as a slightly produced zone reaching the apertural margin.
• On the body whorl a distinct peripheral belt is present on which the growth lines are strongly bent backward, indicating a deep sinus in the apertural margin.
• The apertural margin is not thickened inside, the callus does not cover the umbilicus, the angularis is very weak, the parietal callus is weak or absent, no cervical callus is present.
• The apertural margin in lateral view is oblique / and (-shaped, with an exaggerated sinulus, and a P-like opening at the suture in the last quarter of the last whorl.
• R . singularis is possibly the end of an evolutionary line that begins with an almost straight apertural margin ( in lateral view ) towards a much more oblique and protruded margin with the needle snail having the longest sinulus along the suture.