Dutta and Bardhan—Jurassic ammonite taxonomic corrections
197
1875 Perisphinctes spirorbis, Neumayr; Waagen, pars, p. 154, pl. 40, figs. 1a–c.
1895 Perisphinctes aberrans Waagen; Noetling, p. 22 (pars).
1899 Perisphinctes indicus, Siemiradzki; p. 323 (non pl. 23, fig. 33).
1911 Perisphinctes indicus, Siemiradzki; Till, p. 36. 1924 Grossouvria indica (Siemiradzki) Spath, p. 13. 1930 Indosphinctes indicus (Siemiradzki) Spath, p. 36. 1931 Indosphinctes indicus (Siemiradzki); Spath, p. 333.
Holotype.—GSI type no. 2043.
Occurrence.—Lower Callovian, Keera in the mainland of Kutch.
Figure 2. (1) Septal sutures of Subgrossouvria aberrans Waagen, 1875 at diameter ~156mm, redrawn from Waagen (1875, pl. 40, fig. 1c). (2) Septal sutures of Indosphinctes indicus (Siemiradzki) at diameter ~162mm, redrawn from Waagen (1875, pl. 41, fig. 1c). E = external lobe; L = lateral lobe; U = umbilical lobe. All×2.
lectotype at diameter of ~156mm (pl. 41, fig. 1c), which is refigured here (Fig. 2.1). The lobes are fine, delicate, and highly ramified; the siphonal lobe is broad, long with terminal branches; external saddle not very broad, bifid; first lateral lobe narrow, but longer than the siphonal lobe, highly incised, having asymmetrical trifid lobes; first lateral saddle narrower than the external saddle with long secondary lobe; second lateral lobe indistinct, four auxiliary lobes decreasing in size, hanging down to form a deep sutural lobe.
Waagen (1875) vividly described the suture from this Genus Indosphinctes Spath, 1930 Type species.—Ammonites calvus Sowerby, 1840.
Diagnosis.—Macroconchiate shell large, diameter may exceed 250mm, evolute, and compressed; inner whorls characterized by strong ribs, primary ribs furcate at the middle or slightly higher flanks; primary ribs often bundled or confined to a blunt node; ribs continue or may weaken or disappear completely with the beginning of adult body chamber. Adult body chamber occupies more or less half of the last whorl; peristome unknown. Suture is complex and highly frilled. Microconchs thoroughly ribbed and lappeted.
Occurrence.—France, Germany, England, Poland, Portugal, Hungary, Kenya, Tanzania, Madagascar, Turkey, Caucasus, Iran, Kutch, Baluchistan (Pakistan), Tibet, and Japan.
Indosphinctes indicus (Siemiradzki, 1899) Figures 1.4–1.6, 2.2
Description.—The holotype is represented by mostly internal mold. Specimen with body chamber preserved (maximum diameter = 232mm). It is strongly evolute (ratio between umbilical diameter and the shell diameter, U/D, = 0.52) and highly compressed (ratio between whorl width and the whorl height, W/H, = 0.7). Inner whorl at ~63mmdiameter is evolute (U/D = 0.39), umbilicus wide and shallow, umbilical margin is rounded with steep wall. Flanks are curved with long, numer- ous, slightly prorsiradiate primary ribs (number of primaries per half whorl is 15). Secondary ribs are not visible. At 132mm diameter, specimen is relatively more evolute
(U/D = 0.42) and compressed (W/H = 0.6). The primary ribs become thick and gradually start fading at ~182mmin diameter, which marks the beginning of the body chamber. The body chamber appears to be smooth on the internal mold, but presence of traces of three bullae-like ridges at the preserved end indicates that the apparent smoothness of the body chamber is a preservational artefact. The length of the preserved body chamber is about three-fourths of the outer whorl. Peristome is missing.
patterns of the holotype at ~162mm in diameter (pl. 40, fig.1c), which is refigured here (Fig. 2.2). The lobes are fine and highly frilled; the siphonal lobe longer than broad with deeply incised branches; the external saddle broad, symmetrical with a well- developed secondary lobe; the first lateral lobe narrow, longer than the external lobe, deeply incised and trifid; the first lateral saddle narrow with asymmetrical lobes; the second lateral and four auxiliary lobes are small and hang down rapidly to form a large sutural lobe.
Acknowledgments
We thank theDirector of theCuratorialDivision of theGeological Survey of India, Kolkata for granting access to the type materials. We also thank A. Roy and S. Mondal for critically reading the manuscript. We thank two anonymous reviewers, the editor (B. Hunda), and the associate editor (M. Yacobucci) for critically reviewing the manuscript and providing valuable suggestions. Partial aid from the DST (SERB - SR/S4/ES-638/2012) was received by SB; RD received aid from the UGC-BSR Scheme, Jadavpur University, Kolkata, India.
Waagen (1875) described in detail the septal sutural
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