110 G. LINDSTKOM, ON THE .SILURIAN GAfSTllOFODA AND PTEROPODA OF GOTLAND. 



I. Ph'urut.. sj). ( — ? Eccyliomphulus iihilus ItoicMKU, ? llulicitcs ueutrifiigus Wah- 

 LENBEUCi, si'i! alsu I'l. XV, lijf. 12 — l-l ill "Fraguiciita Siluricii). This is a Miuallcr species 

 tli.in the foniKT, more iiiieoiled and teiidiii"; to couiplete scalarid fonnatioii. Tiie iii- 

 sidr of tlie wliorls is not so steep as in i'l. inai'ginata and the funnel formed on the 

 apical side not so regular as in that. The sculpture is more distinct of coarse trans- 

 verse lines and the slit band is mure pi'ominently alate or laminar than in them. This 

 i)eeurs in the Lower (.Jray Orthoceratite limestone, in the Upper Red and U]i|)er Gray 

 Orthoceratite limestone and also in the Chasmops limestone of Ohiud. 



It is of such forms as tiiis, that the genus Eccyliomphalus has been built up, 

 commingled with others, as evulute Euomphali. To elucidate their distribution in 

 time the following table may serve. 



Divisio IV. SIMPLICES. 



21. Pleurotomaria valida n 



ri. IX tiff. 11—13. 



Shell elongate, turbinated, with seven or seven and a half whorls, which are ven- 

 tricoae, the superior ones forming an obtuse angle midway between the median line 

 of the whorl and the suture where the slit band is situated. 



The whorl is almost flat beneath the slit band sloping suddenly inwards towards 

 the suture. There are only some slight traces left of the sculpture of this uncom- 

 monly thick shell, and it consists in transverse stria\ The slit band is very large, 

 nearly 1 mill, across, the height of the whorl being 27 mill. The aperture is oblong 

 and the columellar lip thick and reflexed, so as to hide the umbilicus of which there 

 is no trace, as the columella is solid. The shell seems to have been much exposed and 

 weathered before it was enclosed in the limestone- 

 It has been found in a hard, crystalline limestone near Lillugn in a wood between 

 the [larishes of Ardre and Alskog. PI. intiata 1\Iac Coy, iSil. Foss. of Ireland p. 15 

 pi. 1 f. 15, somewhat resembles this shell in form. 



') PI. replicata, nearly related to this, is round in the Gotland shale. 



