84 



M.K. HOWARTH 



different species. CA601 has a complete, probably adult, mouth- 

 border at 1 35 mm diameter, thick quadrate whorls, and has umbilical 

 tubercles on the inner whorl, but is smooth from at least 90 mm 

 diameter on its outer whorl; Spiticeras is not usually smooth at large 

 sizes, and except for the tubercles on the inner whorls, the morphol- 

 ogy is more like that of Groebericeras. CA602 is more involute, has 

 a compressed, trigonal whorl section, umbilical tubercles on the 

 inner whorl, and again an apparently smooth outer whorl The 

 specimen from bed 57 at Mintaq is 80 mm diameter, poorly pre- 

 served, and has whorls and tubercles possibly like S. (S.) spitiense. 



Subgenus NEGRELJCERAS Djanelidze, 1922 



Type SPECIES. Ammonites negreli Ma\h&xon, 1880, subsequently 

 designated by Roman (1938: 382). 



Spiticeras (Negreliceras) obliquenodosum (Retowski, 

 1893) PI. 18, fig. 3 



1 893 Holcoslephanus obliquenodosum Retowski: 249, pi. 9, fig. 



18. 

 1922 Spiticeras obliquenodosum (Retowski); Djanelidze: 178, 



pi. 1 1, fig. 4; pi. 20, fig. 3; pi. 21, fig. 6. 

 1 922 Spiticeras obliquenodosum vai.fauriensis Djanelidze: 181, 



pi. 21,fig. 7;pl. 22. fig. 2. 



Material. Three specimens: CA604 from bed 36, CA605 from 

 bed 30 and CA606 from bed 29 of the Mintaq Member, Mintaq Salt 

 Dome. 



Description. CA604 is a complete body-chamber, 100 mm 

 diameter, in which the umbilical seam uncoils slightly just before the 

 apparently intact mouth-border, which is plain and has no trace of a 

 lateral lappet; it is preserved on one side only, the reverse being 

 crushed and eroded; all the inner whorls are missing; traces of 

 suture-lines suggest that the body-chamber is exactly one whorl 

 long; approximate measurements of CA604: at 97 mm diameter: 

 33.0(0.34),-, 37.5 (0.39). The other two are small poorly preserved 

 fragments of single whorls about 60-75 mm diameter and are partly 

 crushed and eroded. 



The whorls are compressed, with nearly flat sides and rounded 

 umbilical and ventro-lateral edges; the venter appears to be narrowly 

 rounded, but is not well seen. The smaller specimens have umbilical 

 tubercles, radial ribs of moderate density, and traces of a few 

 constrictions. The body-chamber of CA604 is much smoother: three 

 constrictions remain and there is another (or a collar) at the mouth- 

 border, but the ribs are reduced to indistinct striae, and the umbilical 

 tubercles, which are large and bullate at the beginning of the body- 

 chamber, rapidly disappear on the final three-quarters of a whorl. 



Remarks. Retowski's holotype and the smaller specimens fig- 

 ured by Djanelidze (1922) are all inner whorls that have ribs and 

 umbilical tubercles, some of which are elongated obliquely back- 

 wards. The only larger specimen described hitherto is the 84 mm 

 diameter example figured as \ds.fauriensis by Djanelidze ( 1922, pi. 

 22, fig. 2), which has large umbilical tubercles and reduced ribs on 

 its last quarter whorl, like CA604. As the only larger specimen 

 known, van fauriensis is probably not different from Retowski's 

 species. Few species of Negreliceras become smooth in their later 

 growth stages, and this is the only one that combines reduced ribbing 

 with large umbilical tubercles. Spiticeras altavensis (Pomel, 1889: 

 67, pi. 6. figs 1 . 2), which has apparently similar tubercles and ribs 

 that fade on the final whorl, might be similar, but it is based on a 

 drawing that cannot be accurately interpreted. Groebericeras also 



becomes smooth at its larger sizes, but the umbilical tubercles 

 disappear as well as the ribs, and it has more involute and massive 

 whorls than the typically compressed and evolute Negreliceras. 



Occurrence. Mintaq Member, Hajar Formation, Mintaq Salt 

 Dome; Occitanica Zone. Berriasian. 



Spiticeras (Negreliceras) paranegreli Djanelidze. 1922 



PI. 16, fig. 5 



1922 Spiticeras (Negreliceras) paranegreli Djanelidze: 108, pi. 

 6, figs 1-3; pi. 12, fig. 5; pi. 22, fig. 1. 



Material. CA607 from bed 3 1 of the Mintaq Member, Mintaq 

 Salt Dome. 



Description. This is a half whorl fragment, 45 mm diameter, in 

 which septa and suture-lines are not preserved. The whorls are 

 moderately evolute, elliptical in cross-section, with a smoothly 

 rounded umbilical edge and a narrowly rounded venter. The inner 

 part of the side of the whorl is smooth or striate, and fine radial ribs 

 occur only on the outer part of the whorl and the venter. No umbilical 

 tubercles are visible. 



Remarks. This ammonite is very similar to one of the examples 

 figured by Djanelidze (1922: pi. 6, fig. 1 ), which has a smooth inner 

 half of the side of the whorl and no umbilical tubercles. Djanelidze's 

 specimen is a complete microconch. with a long lappet in the mouth- 

 border at 56 mm diameter, which is only a quarter of a whorl larger 

 than the Yemeni specimen. Two other Djanelidze specimens are 

 complete microconchs at 63 mm diameter and incomplete at 70 mm 

 diameter. 5'. {N.) paranegreli is the only species of the subgenus in 

 which ribs and tubercles are reduced or absent. 



Occurrence. Mintaq Member. Hajar Formation, Mintaq Salt 

 Dome; Occitanica Zone, Berriasian. 



Family ATAXIOCERATIDAE Buckman, 1921 



Subfamily ATAXIOCERATINAE Buckman. 1921 



Genus CRUSSOLICERAS Enay. 1959. p. 230 



Type species. Ammonites crussoliensis Fontanncs, 1876. 



Synonym. Badenia Enay, 1959, p. 230; type species, Badenia 

 wegelei Enay. 1959. p. 230 (nom. nov. for Perisphinctes acerrimus 

 Siemiradzki.Wegele, 1929: 62.pl. 5.fig. 4(«o«Siemiradzki, 1891)). 



Remarks. Crussoliceras is a distinctive genus that is confined to 

 the Divisum Zone at the top of the Lower Kimmeridgian. so its 

 presence in the upper half of the Billum Member is important for 

 dating. Tie Perisphinctes-Vike primary ribs of the inner whorls 

 become very widely spaced and trifurcate or multiplicate on the 

 outer whorls in Crussoliceras, which also has distinctive collared 

 constrictions. The type species of Crussoliceras is based on a 

 specimen that is probably a macroconch, while that of Badenia is 

 probably a microconch There are well-formed lappets in some 

 species, eg. in C. divisum (Quenstedt, 1888: pi. 106, fig. 1; Geyer, 

 1961: pi. 3. fig. 5). The similar, but probably unrelated, genus 

 Katroliceras of the Hybonotum Zone develops more massive, thicker 

 whorls, and larger primary ribs than Crussoliceras. 



Crussoliceras cf. wegelei Enay, 1959 



Fig. 4 



1929 Perisphinctes crussoliensis Fontannes; Wegele: 61. pi. 6, 



fig. 1. 

 1929 Perisphinctes acerrimus Siemiradzki; Wegele: 62. pi. 5, 



figs 4, 5. 



