﻿SOLARIUM. 



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Straparollus exsertus is a fossil of the Murchisonx-zone of Bradford Abbas and 

 Coker, where it is extremely rare. Fig. 4 represents a more depressed variety 

 from North Dorset, but the precise horizon and locality are unknown, 



254. Straparollus, cf. altus, d'Orbigny, 1853. Plate XXVI, fig. 5. 



1852-3. Stbapabollus altus, d'Orb. Terr. Jur.. vol. ii. p. 314, pi. cocxxxii, 



figs. 5— 8. 



Description : 



Diameter . . . . .11 mm. 



Height . . . . .10 mm. 



In the specimen under notice the width and height are nearly equal ; spire 

 about one-fifth the total height. The whorls externally (six) are sub quadrangular 

 to trigonal, flat atop, and occur in steps. The marginal tuberculations are well 

 developed and rather close. The upper angle of the body- whorl is a right angle, 

 but the flank rapidly contracts towards the umbilicus, which is of moderate 

 dimensions and surrounded by a few large and pointed tubercles. Aperture 

 trapezoidal and produced in front. 



Relation* and Distribution. — This form seems to be a further step in the direction 

 of Solarium; though about three times the size of d'Orbigny's type from the 

 Bathonian of Langrune, the resemblance is strong. A single specimen from the 

 Inferior Oolite near Beaminster. 



Note. — Besides the species of Discohelix and Straparollus enumerated above, 

 we find here and there throughout the Inferior Oolite specimens which from 

 imperfect preservation it is impossible to diagnose, e. g. below the Opal inns-bed 

 at Burton Cliff. Again, there is a very thin form in the Opalinus-beA of the 

 same locality : a similar form occurs in the blue stone at Duston. 



Genus — Solarium, Lamarck, 1799. 



Shell orbicular, conical-depressed, largely umbilicated ; whorls subtrigonal and 

 sloping ; spire regular, nucleus oblique; umbilicus deep, the outer margin crenulated ; 

 aperture trapezo idol . 



D'Orbigny seemed to entertain no doubt as to Solarium having been a Jurassic 



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