Palaeontographical Society Monographs Volume 9, Nos. 33-38 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1848 edition. Excerpt: ...between their forms and ornaments in the young and older stages of their growth, excepting near the produced mouth; so that the species may be recognised in specimens of any size or age. None of the group of the rotumlati have been found with the produced mouth like the Tarrilites, and the only modification known in the adult shells of that group is a thickening of the edge of the mouth: probably this will be found to be another generic difference between Ylzrrilites and Helicoceras. Classgfication of Turrilites. l. ROTUNDATI, 1701-5. Whorls round; siphuncle near the middle of the exterior side of the whorl; ribs simple; mouth thickened. Common in the Gault. T. acuticostatus, D'Orb. C. C. 2. ANGULATI, D'Orb. Whorls angular; siphuncle near the suture; mouth covered with a hood. 2 a. Lateral lobe trifid; ribs or tubercles not arranged in regular lines across the whorl. T. tuberculatus, Bosc. L. Chalk. T. Gravesianus, D'Orb. Pl. 144, fig. 3. L. Chalk. T. Zllanielli, Sharpe. 2aa. Lateral lobe trifid; tubercles in regular rows across the whorl.. T. Beryeri, Brong. Gault and L. Chalk. 2 5. Lateral lobe bifid; tubercles or ribs arranged in regular lines 2c. Lateral lobe bifid; tubercles not in regular rows across the whorl. T. Jllorrisii, Sharpe. U. G. Sand and L. Chalk. 7'. team' lurritri, sinistrorazi: anfractibus nurnerosis, extra' convewis, tuberculate-.spz'n0sz's.tueerculis 4-serialibus; serie superiori, in media anfractuum, tuberculis 20 distantibua, ma.m'mz's, spinosis, -seriebus frieus inferioribus prope suturam tuberculis parvis, numerosis, approwirlzalis: rmyulo apirali I6--20. Shell turreted, with a spiral angle of 16 to 20, sinistral: whorls numerous, rounded externally, with one row...