KONGL. SV. VET. AKADEMIENS IIAN])L. BAND. 19. N:0 6. 149 



foi'mation of tlie uinbilical side in soinc way reminds of thc aijpeararice of tlie same 

 side in Trochita and Galerus, but pcrhaps more so of that in Onustus or Phorus 

 (f. inst. Pil. uxutus). Tlieir great accordance witli such Jurassic forins as Trochus 

 lamellosus D'OiiBiGNY is also already above indicated. There is also a Lower Silurian 

 genus Clisospira, iirst described by Billings in Canada, and also found in tlie beds of 

 the red Trinucleus shale of Östergötland, nearly allied to these forms. 



7. Troclius cavus n. 



Pl. XVIII fig. 15—17. 



Shell broadly conical, with a large periphery of the umbilieal side and obtuse 

 apex. Whorls fivc or six, of faintly concave outline, transversally striated, striaj gently 

 arched, distantiated with smooth interstices. Section of whorls transversally elliptic. 

 The suture is completely hidden by the superior borders of the whorls, which have 

 eoalesced with the younger whorls and thus form an even apex. The umbilieal side 

 is a deep, cup shaped hollow, more like that of a Phorus than that of the preceding. 

 The encircling borders of the shell are higher and thinner. In a shell of 17 millim. in 

 length there is a vertical height of 10 millim. for this umbilieal hollow. Its surface 

 Is almost smooth, only with indistinct, transverse strias. The bottom, a gently eleva- 

 ted belt around the umbilicus, is formed by the upper side of the body whorl, which 

 is more flat and expanded than in Tr. profundus. It is separated from the thin lips 

 of the börder through a slightly elevated, narrow, annular stripe. The aperture is 

 ovate, lips thin and sharp, the umbilicus is open and wide. Height 9 millim, br. 20 mm. 

 Another specimen h. 14 mm., br. 22 mm. Fragment of a large specimen 30 mm. 

 in breadth. 



Some specimens have been obtained in the red and gray limestone beds of the 

 hills of Linde and Sandarfve. 



8. Troclius Lundgreni n, 



Pl. XIV fig. 46—53. 



Shell large, broadly conical, whorls eight, rapidly increasing, slightly convex, 

 superior börder enlarged into a broad lameilar ridge, horizontally outstanding and 

 separating the umbilieal surface from the apical. This ridge is visible on all whorls 

 and projecting beneath the shallow suture. As seen in the magnitied section of this 

 ridge, lig. 52, its interiör cavity has been divided through about five, transverse dia- 

 phragms. On looking at fig. 47 and the magnified corner of the aperture, it can be 

 questioned whether these apparent interiör, transverse diaphragms are not rather to be 

 regarded as the sections of several such apertural edges, as seen in fig. 47, formed 

 inside each other, every new one smaller than its predecessors. In fig. 53, showing a 

 weathered edge, there are also some such apertural corners brought forward. The 

 ornamentation consists of narrow oblique sigmoid strise. On the slightly convex 



