KONGL. SV. VKT. AKADEMIENS UANDL. I5AN1J. 19. N:0 6. 149 



foiiuatioii ut tlie umbilical side; in some way reminds ut the appearance of the same 

 side in Trochita and Galerus, but perhaps more so of that in Onustus or I'hurus 

 (f. inst. Ph. exutus). Their great accordance with such Jurassic forms as Trochus 

 lamellosus DOubigny is also already above indicated. There is also a Lower Silurian 

 genus Clisospira, lirst described by Billings in Canada, and also found in the beds of 

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



7. Troclius cavus n. 



PI. XVIII fig. 15—17. 



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

 apex. Whorls five 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 

 coalesced with the younger whorls and thus form an even apex. The umbilical 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 umbilical hollow. Its surface 

 is almost smooth, only with indistinct, transverse striai. 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 border 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. 



PI. XIV fig. 46—53. 



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

 superior border eidarged into a broad lamellar ridge, horizontally outstanding and 

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

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

 ridge, fig. 52, its interior 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 interior, transverse diaphragms are not rather to be 

 regarded as the sections of several such apei'tural 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 cornei's brought forward. The 

 ornamentation consists of narrow oblique sigmoid stria;. On the slightly convex 



