190 G. LINDSTROM, ON THE SILURIAN GASTROPODA AND PTEROPODA OF GOTLAND. 



This genus should, according to Mac Coy be characterized through its remar- 

 kably convex whorls, which are ornamented by »slightly arched striajw or even cancel- 

 lated by transverse and spiral str'nxi. De Koninck's Aclisina then seems in no parti- 

 cular to differ from Holopella. The specimens are generally small. It has probably 

 occurred in the Lower Silurian of Sweden; at least Loxonema dalecarlicum Lindstrom^) 

 may rather be classed with Holopella and it is derived from the Leptacna Limestone 

 of Dalecarlia. In the Upper Silurian of Sweden there are three species, described be- 

 low. The genus has continued during the Devonian, the Carboniferous and probably 

 also during the Triassic times. 



o 



L Holopella teres n. 



PI. XV fig. 61. 



Shell elongate, thick, with seven whorls, which are smooth and transverse, twice as 

 wide as high, with glossy surface. Aperture circular, outer lip thin, the inner lip thick, 

 large and reflexed not only over the umbilicus, but also at the lower edge of the aper- 

 ture. H. 6 mill., br. 3 mill. Found in Slite. 



2. Holopella regularis n. 



PI. XV fig. 12—13. 



Shell moderately large, elongate, turriculate, with five ventricose whorls, separated 

 by a deep suture. The surface is smooth, glossy, covei'ed by extremely fine, slightly 

 sigmoidally wound lines, the aperture ovate, below acuminate, with sharp and thin 

 lips. Umbilicus deficient. H. 21 mill., br. 10 mill. The aperture 8 mill, heigh, 6 

 mill, broad. The specimen figured belongs to Adjunct M. Klintberg, who found it in 

 the shale beds of Wisby. It has also been found in the shale of Petesvik in Habblingbo. 



3. Holopella minuta n. 



PI. XV f. 63. 



Shell one of the tiniest found, being so uncommonly narrow in relation to the 

 length, regularly elongated and slender of eight globose whorls, one and a half time 

 as wide as high, regularly striated with fine, curved lines, having their greatest bend 

 along the median line of the shell. H. 7 mill., br. 2 mill. Occurs frequently in the 

 red limestone of Sandarfve kulle. 



Fam. Xin. PYRAMIDELLIDiE Gray. 

 Gen. MACROCHILINA Bayle. 



1841 Macrocheilus Phillips Palreoz. Foss. Cornw., 103. 



1842 Plectostylus Conkad Proceed. Ac. N. Sc. Philad. 275. 



') Angelin & LiNDSTROM, Fragmeuta Silurica p. 14, pi. XV, f. 19. 



