112 (i. LINnSTRÖM, ON TIIE SILURTAN GASTROrODA ANT) PTEROrDDA OF GOTLAND. 



Delphinula mquilatera 1829. Hisingeu Tableau Ed. 1, 10, 



1S31. 111. Tablciiu Ed. 2, 8. 



1831. Id. Anteckn. 5, 113. 



Eiiomphaliis cequilaterns 1837. II). Letlirea, 36, tali. XI F. 8. 



1841. Id. Förteckning, 55. 



Pleii.rotomaria m/päl.atera 1848. Bronn Nomonclator, 1012. 



St.rnparollua cequilatcrus 1850. DOrbigny Prodr. I, 29. 



Shell globular or disciform, with short spire of seven whorls, resembling those 

 of an Helix. The slit band is only a little below the middle of the body whorl, and 

 close to the suture, near the upper börder of the other whorls. It is narrow and open 

 for a long way from the aperture on the body whorl. Its surface is even and the 

 bordering lines are lamellar, projecting. No definite sculpture is discernible owing to 

 its considerable narrowness. The surface of the shell is sculptured with fine, recurved 

 transversal lines. The whorls are somewhat flattened below the slit band, ronnded on 

 the unibilical surface. The aperture is transversally oval, the umbilicus wide, and all 

 whorls visible. Diameter 45 millim., height 20 millim. 



Occurs in the shale beds (a) at Wisby, in the limestone of Samsugn in Othem, 

 Stor Wede at Follingbo, Westuös in Hall, Kyrkberget of Wisby, Kålens Qvarn near 

 Wisby, the hill of Bara, Wialmsudd at Fårösund and also Fårö, Lutterhorn and Stor 

 Myr in Rute. The Mineralogical Cabinet of the Universitj^ of Upsala has a speciraen 

 collected by Professor P. T. Cleve in the limestone of Slite. 



There exists a great variability in this shell, especially as to the width of the 

 umbilicus and the height of the spire as remarkable through the figures of the typical 

 specimen of Wahlenberg, which has been kindly lent from the Mineralogical Cabinet 

 of Upsala, with its low spire and flattened whorls to these globose shells delineated in 

 the figs. 26 and 27. Through the former, fig. 20 — 22, there can be no doubt of what 

 Wahlenberg really meant by his species. But there is no reason with him and Hi- 

 singer to suppose that it also has been found in the Lower Silurian. I have not 

 seen a single specimen from that formation appertaining to this species. In Hisinger's 

 own collection there are specimens from Holmestrand in Norway, badly preserved, and 

 by him called Euomph. a3quilaterus. One specimen, the best, may possibly belong to 

 this species. In the same collection there are also specimens from Gotland called 

 Euomph. ajquilaterus. Thej^ are five, miich worn specimens of Oriostoma discors from 

 Kapellshamn and one specimen of Pleurotoraaria undulans. Eichwald, Leth. Rossica I, 

 II, 1170, adopts also this species, but the Identification is questionable, as well as that 

 of K.JERULF in Veiviser p. 24. 



Sociotatis Uegioe Snientianini" was indeed printcd already in 1818, as Wahlenberg himself says in the 

 beginiiing of tlie »Additamenta» to tliat mcmoiv, page 293 of the same volume. The statement there 

 given is: »Postquam anno 1818 impressa fuerat Commentatio de Pctrificatis Svecanis" etc. The me- 

 raoir had also been early enoiigh distvibuted tiy its anthor to some geologists, as can be perceived by 

 what BiioNGNiAKT says in his »Crustarés fossiles" (1822) p. 2, viz.n . . M. Wahlenberg, ilont le tra- 

 vail . . . n'est venn a ma eonnaissance qu'en 1819». Rnt on the title page of volurae VIII, eontaining 

 the collected memoivs and papers, the year 1821 is printed, as it was not issued cotnplete before 

 that year. 



