Trof. T. Rupert Jones — Fossil Estherice. 53 



they are much crushed, and Fig. 14 shows one of the best. It is 

 very much like the German specimen figured in tlie Gbol. Mag. for 

 September, 1890, PI. XII. Fig. 6, aud nearly matches fig. 9 of pi. ii. 

 " Monogr. Foss. Esth." 



E. miniita, var. Brodieana, has been reported by Ferd. Eoemer as 

 having been found in the Keuper of Upper Silesia. This, and some 

 other notes on the occurrences of E. miniita published since 18G2, 

 are given in the Geol. Mag. Dec. II. Vol. V. 1878, p. 102. 



E. minuta, var. Karpinskiana, Jones, related to var. Brodieana, 

 was obtained by Dr. Karpinsky from the Triassic or Ehastic strata 

 of Troizk, on the eastern side of the Ural. See Ann. Mag. Nat. Hist., 

 October, 1883, p. 244, pi. vi. fig. 1. 



EsTHERiELLA, Weiss (as a subgenus, 1875). 



Similar to Estheria, excepting that the valves bear radial riblets 

 or slight ledges crossing the concentric strise from near the umbo 

 to the ventral border. 



5. EsTHERiELLA cosTATA, Weiss, 1875. PI. II. Figs. 9, 10, a, b. 



PosicJonomya Wengensis, Giebel (non Wissmann). Zeitsch. gesammt. Naturwiss. 



Halle, 1857, p. 308, pi. ii. fig. 6. 

 JEstheria ? Wengensis, Alberti. Ueberblick Trias, etc., 1864, p. 192. note. 

 Estheria [Estheriella) costata, Weiss. Zeitsch. D. g. Gesellsch. vol. xxvi. 1875, 



p. 711, note. 

 Estheriella costata, Zittel. Handbuch der Palseontologie, vol. i. Lief. 8, 1885, p. 568. 



Fig. 9. — Length 3-7 (hinge-line 2-7), height 2-4 mm. 



Valves like those of Estheria minuta, such as those shown by pi. i. 

 fig. 29, and pi. v. figs. 8 and 9, "Monogr. Foss. Esth.," that have 

 markedly straight backs, a more or less definite postero-dorsal angle, 

 and strong concentric lines of growth (about 18 visible). Modifica- 

 tions produced by pressure, as well as by variable conditions of 

 growth, make it difficult to find perfectly comparable specimens 

 among fossil Estherice. The characteristic feature is the presence 

 of numerous (about 20 or more) oblique stria3 radiating from the 

 middle region to the ventral and posterior borders. Posteriorly they 

 produce a series of undulating wrinkles, crenulating the edge ; but 

 more forward they seem to have been little furrows formed by the 

 notches in the edge of each successive overlapping lamina of the 

 test, and giving a minute tile-like appearance to that part of the 

 surface. A pattern somewhat like this, but on a still smaller scale, 

 is visible in Estheria tegulata from the Scotch Coal-measures, to be 

 published in the Trans. Geol. Soc. Glasgow, vol. ix. pi. v. fig. 66. 



In the Estheriella under notice the edge of each lamina is more or 

 less thickened at and between the notches, and was there sufficiently 

 produced as little hollow tubercles to leave the minute pits seen 

 in the inside of the test (figs. 10 a, h). Here, also, there are traces 

 of this structure reaching further up towards the umbo than on the 

 outside (Fig. 9). 



The specimens of both this and the next species are very delicate 

 and scarcely ever perfect films of valves in bluish grey shale. 



