290 Professor T. Rupert Jones — 



it would be impossible, without more knowledge of the internal 

 structure, to recognize a generic identity. 



An approach to this rare form (Cydestheria) among Estheria is 

 seen on pi. iv, fig. 3, " Monogr. Foss. Mstherice" a right-hand valve of 

 a small form (possibly a variety) of E. elliptica, from the Purbeck of 

 Hanover, and already referred to. 



Both Forbes's specimens and Philippi's outline are matched to some 

 extent by Krotow's Estheria snhconcenirica, Fig. 7, from the " Lower 

 Permian " formation of the Urals ; ^ but this apparent alliance is not 

 sufficient to give a geological horizon to the Arica shales. The 

 doubt, moreover, of the locality and geological horizon whence 

 E. Chilensis really came, further obscures the possible relationship 

 of these Esiherice. 



§ IX. SZAJNOCHA, 1888. 



In the " Verhandl. k. k. Geol. Eeichsanstalt Wien," 1888, pp. 146, 

 147, Dr. L. Szajnocha refers to specimens collected by Dr. Eudolf 

 Zuber in South Argentina and Patagonia, especially plant-remains, 

 such as characterize Triassic or Ehsetic strata in Australia, South 

 Africa, Germany, Portugal, and Scania. He notices that at Cacheuta 

 shales with plant-remains and phyllopoda occur, and that the latter 

 were described by Geinitz as Estheria Mangaliensis, Jones, in his 

 Memoir (1876) on these and other Ehsetic plants and animals. 



§ X. Summary of the Foregoing Notes. 

 These result in the determination of four species of Estheria found 

 fossil in Peru and Chili, namely — 



1. Estheria Mangaliensis, Jones, Mangali in Central India, and 



Mendoza in South America. 



2. E. Forbesii, Jones, Mendoza, South America. 



3. E. Aricensis, sp. nov., Arica, South Peru. 



4. E. Chilensis, Philippi, Lebu (?), Chili; Arica, South Peru. 



§ XI. Estheria Mawsoni, sp. nov., and var. 



There is also another South-American Estheria preserved in the 

 British Museum (Nat. Hist.), and forming part of Mr. J. Mawson's 

 Collection from Brazil, namely (5) Estheria Mawsoni, sp. nov., and 

 (5'''') variety. 



(5) Estheria Mawsoni, sp. nov. 

 PLATE XI, Yigs. 2,a-g. 



Carapace obliquely subovate, moderately gibbose. Umbones at 

 the anterior third of the valve. Hinge-line straight from the umbo 

 to the posterior end, and equal to about two-thirds of the length of 

 the valve. Hinder moiety of the carapace smaller than the front part, 

 the posterior curve being more contracted than the antero-ventral 

 curve. Hence the carapace has a triangular subovate side-view. 



Concentric ridgelets or lines of growth, numerous : more than 

 thirty, although those on the umbonal area are obsolete or obliterate. 

 These ridges on the upper part, just below the umbones, are strong, 



1 Mem. Com. Geol. (St. Petersburg), vol. vi, 1888, pp. 469 and 556, pi. ii, 

 fig. 26. See also Brit. Assoc. Report tor 1889, p. 66. 



