226 G. LINDSTKOM, ON THE SILURIAN GASTKOPOUA AND PTEROrODA OF GOTLAND. 



Plate X. 



Fig. 1. Pleurotomaria latezonata n., p. 99. 



" 2 — 17. » limata n., p. 114, f. 2 — 5 from Klinteburg, f. 6 — 9 from the middle limestone 



strata of Wisby, f. 10 — ^11 variety from the canal near Westoos in Hall, f. 12 specimen from 

 Wisby seen from the umbilical side with a largely developed slit band, f. 13 details of 

 ornamentation of the slit band and the surface around the umbilicus, f. 14 transverse section 

 of the slit band, imbedded in fine grained rock, f. 15 — IG slit band of two different specimens, 

 magnified, f. 17, part of a slit band cloven in two parts along its median line to show how 

 the crescentic lamelhe continue outward to the thin bordering lines. 



" 18 — 32. Pleurotomaria (data His., p. 116. All the originals to the figures from Wisby. Fig. 23, 

 near the aperture the crescentic lamellae between the bordering laminae are conspicuous as 

 black lines below the surface and they are partially restored by dotted lines where they have 

 been broken away, f. 24 inferior surface showing the wavy edge of the slit band, f. 25 

 ornamentation of umbilical surface, f. 27 details to elucidate the structure of the slit band, 

 f. 28 ornamentation of apical surface from a specimen with a ridge, f. 30 transversally 

 sectioned slit band, magnified, f. 31 extreme edge of a slit band, f. 32 variety from Wisljy 

 with downwards anh inwards curved slit baud. 



" 33 — 37. Pleurotomaria abita, var. subcarinata n., p. 118, "f. 33 specimen from Lingsarfve in Nas, enclosed 

 in an oolitic nodule, figs 34 — 37 from Djupvik in Eksta. 



» 38 — 40. Pleurotomaria alula, var. opposita n., p. 119, from Habblingbo, f. 39 apical side of body 

 whorl and part of next whorl, f. 40 ornamentation of umbilical side and slit band. 



