PLATE 4. Disarticulated specimens of Leptothyrellopsis polonicus Bitner & Pisera, 1979 from various chalk deposits of early late Campanian to early Maastrichtian (Belemnella obtusa Zone) age, at a number of localities in Belgium. Size of the specimens indicated by scale bars. Fig. 1. Specimen RBINS–IST.10725 from Ciply-Malogne Phosphatic Chalk Formation (lower Maastrichtian, Belemnella obtusa Zone) at Ciply (Hainaut, Belgium). In this specimen the crura are broken and not visible, except for the crural base of the right one in Fig. 1c. 1a: Ventral valve in dorsal view. The valve floor is smooth. In the obtuse beak, the foramen is bordered by narrow, but protruding deltidial plates. The smooth sessile pedicle collar with a weak step-like aspect is clearly visible. 1b: Detailed oblique anterior view of posterior part of ventral valve showing divergent dental plates and smooth sessile pedicle collar. 1c: Dorsal valve in ventral view. The long, large blade-like septum and thin crural plates (arrowed "p") are the most important characters illustrated in this view. 1d: Oblique lateral view showing strong inner socket ridges, crural plates and septum. This one is partially broken in its posterior part, but this shows that the septum is made of two layers pressed against each other (arrowed "*"). 1e: Anterior oblique view highlighting the structure of crural plates. They cannot be confused with inner hinge plates forming a septalium. 1f: Posterior view showing clearly the two layers building the septum. Fig. 2. Specimen RBINS–IST.10726 collected from the Ciply-Malogne Phosphatic Chalk Formation (lower Maastrichtian, Belemnella obtusa Zone) at Ciply. 2a: Ventral valve in dorsal view. The teeth are broken. There is a faint ridge in the centre of the valve. 2b: Lateral-oblique view of ventral valve. The faint ridge in the centre of the valve is more distinct. The strong divergent dental plates are clearly visible. 2c: Dorsal valve in ventral view showing the blade-like septum and crural plates. Crura are broken. 2d: Posterior view. 2e: Anterior view. 2f: Oblique lateral view showing the cockscomb outline of the septum with its strongly concave posterior part. Fig. 3. Specimen RBINS–IST.10752, from top of Trivières Chalk Formation (Craibel quarry, Cuesmes, Mons Basin, Hainaut, Belgium), lowermost upper Campanian (Belemnitella mucronata Zone). 3a: Dorsal valve in ventral view. The septum is partially damaged in its posterior part. In this specimen the crura are completely preserved and a portion of the recrystallised schizolophe lophophore is preserved. 3b: Detailed view of the crura in ventral view. 3c: Anterior view. 3d: Oblique lateral view. 3e: Detailed view of the socket with strong inner socket ridge, of the crus and of the crural plate. Fig. 4. Specimen RBINS–IST.10753, from top of Trivières Chalk Formation (Craibel quarry, Cuesmes, Mons Basin, Hainaut, Belgium), lowermost upper Campanian (Belemnitella mucronata Zone). This specimen is very clean and shows better the inner structures. 4a: dorsal valve in ventral view. The punctation of the shell is completely exposed. The septum is intact and crural bases are exposed. 4a: dorsal view. 4b: oblique anterior view showing the crural bases. 4c: oblique lateral view of the valve showing the cockscomb outline of the septum with its strongly concave posterior part. At the base of the posterior part of the septum the two layers building the septum leave a free hollow space (bifurcate structure). The two weak ridges joining the base of the posterior part of the septum and the bases of the crural plates are here clearly visible. 4d: oblique lateral view showing again the septum. In this well-preserved specimen a weak ridge (myophore) is perceptible in the posterior portion of the valve floor. Fig. 5. Specimen RBINS–IST.11499 from top of Nouvelles Chalk Formation (upper part of upper Campanian) at Nouvelles (Hainaut, Belgium) in a small, disused quarry near the River La Wampe (co-ordinates 50°24'51"N/3°58'19"E). 5a: ventral valve in dorsal view illustrating well the sessile smooth pedicle collar with its weak, step-like aspect. 5b: dorsal valve in ventral view. 5c: detailed oblique anterior view of posterior part of dorsal valve. The crura are broken but the ridges forming a "V" between the posterior part of the septum and the bases of the crural plates are pointed out (cp). 5d: lateral-oblique view illustrating the cockscomb outline of the septum. In this material the length of the septum is reduced. 5e: lateral view.