AMMONITES AND NAUTILOIDS OF WADI HAJAR 



ventro-lateral angles and venter. From about 70 mm diameter the 

 whorl section becomes typically quadrilateral or almost square, then 

 above 150 mm diameter the whorls become more compressed but 

 still retain the quadrate appearance. Primary ribs are of moderate 

 density on middle and inner whorls, becoming slightly fewer and 

 more distant beyond 150 mm diameter. Typical densities are 45-50 

 ribs per whorl up to 150 mm diameter, decreasing to 40-45 at larger 

 sizes. Most ribs are sharply biplicate, a few remain single, and from 

 100 mm diameter there are a few extra secondary ribs. Ribs cross the 

 venter radially and are slightly diminished along the mid-siphonal 

 line. There are two or three oblique constrictions per whorl up to 150 

 mm diameter, which tend to disappear at larger sizes. 



Measurements 



D Wh Wb U 



C.52840 (cast), 133.0 34.4(0.26) 36.5(0.27) 73.2(0.55) 



lectotype 

 P.beyrichi 71.0 21.0(0.30) 24.8(0.35) 32.7(0.46) 



lectotype 

 P.beyrichi 170.0 50.0(0.29) 52.0(0.31) 81.0(0.48) 



paralectotype 

 P.beyrichi 60.0 19.8(0.33) 25.0(0.42) 27.0(0.45) 



paralectotype 

 CA982 148.0 39.0(0.26) 43.0(0.29) 77.5(0.52) 



CA995 220.0 56.0(0.25) 51.5(0.23) 110.0(0.50) 



CA985 — 70.0 62.0 — 



CA986 — 64.0 55.0 — 



Remarks. A plaster-cast of the Cutch lectotype is figured in PI. 5, 

 fig. 1 for comparison withWaagen's( 1875: pl. 50, fig. 1) drawing. At 

 1 36 mm maximum diameter, it is clearly an incomplete microconch, 

 because it compares exactly with similar-sized parts of a complete 

 Cutch microconch figured by Spath ( 1 93 1 : pi. 77, fig. 1 ), which has 

 a mouth-border and large lappets at 165 mm diameter. Compared 

 with these and the many other Cutch specimens listed in the syn- 

 onymy, the examples from Yemen are mostly fragments, but at least 

 the collection contains parts of large body-chambers of macroconchs 

 (PI. 7, fig. 5), which are presumably near-adult at their largest sizes, 

 which indicate diameters of 275-300 mm. Such macroconch body- 

 chambers, with compressed quadrate whorls and ribs of moderate 

 size and density, are very different from the massive depressed 

 whorls of P. major macroconchs that have very large and thick 

 primary ribs. The differences between the two species are very clear 

 in macroconchs, but microconchs are much less distinct, having ribs 

 of similar size and density, and it is only at diameters of 100 mm or 

 more that the whorl breadth off! wo/or becomes sufficiently large to 

 provide a reliable distinction from P. bathyplocus. A more complete 

 macroconch, though still seriously defective in preservation, is 

 figured in Fig. 2; it has at least half a whorl of body-chamber and an 

 incomplete aperture at 235 mm diameter. The small inner whorls 

 from Naifa Cliff figured in PI. 7, fig. 2, are closely similar to the 

 Cutch lectotype. 



The lectotype of Perisphinctes beyrichi Futterer (1894: pi. 2, fig. 

 2) from Mombasa, Kenya, and other specimens figured by Verma & 

 Westermann (1984) do not appear to differ from Pachysphinctes 

 bathyplocus in any feature worthy of specific separation, ie. whorl 



53 



proportions, rib-densities (at 75 mm diameter there are 45 ribs in 

 Futterer's lectotype, 47 inWaagen's lectotype) and styles of ribbing 

 are almost identical. Specimens from East Africa are known only to 

 diameters of 170 mm, at which size the distinctive compressed 

 whorl section of P. bathyplocus is not fully developed. Six speci- 

 mens from the Hybonotum (? and Beckeri) Zones of Madagascar 

 were figured under six different names by Collignon (1959) (see 

 synonymy ). They exhibit all the typical characters oiP. bathyplocus. 

 and four of them (Collignon, 1 959: figs 444, 445, 447, 475) are from 

 the same bed and locality. 



Occurrence. Lower, middle and upper parts of the Kilya Mem- 

 ber, Naifa Formation, Wadi Kilya, Naifa Cliff and Wadi Arus; 

 Beckeri Zone, Upper Kimmeridgian and Hybonotum Zone, Lower 

 Tithonian. 



Pachysphinctes major Spath, 1931 



PI. 6, figs 1. 2; PI. 7, fig. 1; PI. 8, fig. 2 



1875 Perisphinctes torquatus (J. Sowerby); Waagen: 191, pi. 54. 

 1 925 Perisphinctes cf linki Choffat; Stefanini: 145, pi. 27, fig. 2. 

 1 93 1 Pachysphinctes major Spath: 489, pi. 75, fig. 1 ; pi. 78, figs 



l,2;pl. 87, fig. 3;pl. 89, fig. 6. 

 1931 Pachysphinctes robustus Spath: 491, pi. 84, fig. 5; pi. 93, 



fig. 10. 

 1931 Pachysphinctes crassus Spath: 492, pi. 85, fig. 3. 

 193 1 Pachysphinctes linguiferus Spath: 496. pi. 97, fig. I ; pi. 98. 



fig. 5. 

 1959 Pachysphinctes linguiferus Spath; Collignon: pi. 1 18, fig. 



446. 

 1959 Pachysphinctes major Spath; Collignon: pi. 1 19, fig. 449. 

 1959 Pachysphinctes robustus Spath: Collignon: pi. 120, fig. 



451. 



Lectotype. The original of Waagen, 1875, pi. 54, here desig- 

 nated. 



Material. 46 specimens from the Kilya Member: 5, CAl 157-61 

 from the upper marly part, 11, CA II 62-71 and C. 86962 from the 

 upper part of the middle limestone part, CAl 172-73 from the base 

 of the same part, all in Wadi Kilya; 23, CA996- 1 1 6, SM F 1 2 1 94a 

 and F 12204, from the base of the middle limestone part in Naifa 

 Cliff; 5, CA731-34 and SM F 12167 from the Breadloaf Concre- 

 tions in the lower marly part of the Kilya Member in the east cliff of 

 Wadi Arus. 



Description. Many of the 46 specimens referred to this species 

 are fragments of body-chambers of 150-200 mm diameter, though 

 there are a few much larger, more complete specimens. The largest 

 is 420 mm diameter and consists of a massive body-chamber 320° 

 long from the last septum at about 250 mm diameter, but the final 

 mouth-border is missing. On inner whorls the whorl section is 

 slightly depressed, then becomes much more depressed and massive 

 from 150 mm diameter. Primary ribs are sharp, mostly biplicate and 

 of moderate density (42-50 per whorl) up to 100-150 mm diameter, 

 and there are a few single and triplicate ribs. From 150 mm diameter 

 the primary ribs become much more widely spaced and bold, finally 



PLATE 5 



Figs 1, 4 Pachysphinctes bathyplocus (Waagen). 1, lectotype. Middle Katrol beds, Katrol Range. Cutch, India (figured Waagen, 187.'5. pi. .SO. fig. I ), BM 

 C.52480 (plaster-cast), xO.75. 4a, 4b, base of middle limestone part of Kilya Member (fauna 7). Naifa Cliff. SM F. 12196, wholly septate. 



Fig. 2 Pachysphinctes mahokondoheyrichi (Dietrich), base of middle limestone part of Kilya Member (fauna 7), Naifa Cliff, CA!()17. 



Fig. 3 Perisphinctes (Perisphinctes) sp. indet.. Upper Storm Bed, Madbi Formation (fauna .^), 1 km east of road, south of river crossing at A! Ma'abir. 

 CAI288, xO.72. 



