292 P>'of. T. R. Jones — Fossil Entomostraca from 8. America. 



of shape may possibly be due to sexual condition, since tbe ornamen- 

 tation is quite the same on the two forms. 



Approximately similar valves are found in the varieties of 

 ^. minuta and its allies. This form is somewhat like the carapace 

 of the female JE. Packardi, as figured by Sars. 



Flattened easts of the valves occur in brownish shales and in pink 

 c'lay in the Pitanga and Pojuca cuttings. A carapace from the 

 cutting between Periperi and Olaria measures: Long 5*0 mm., high 

 35 mm., thick 2*5 mm. 



Estlieria Mawsoni or its variety occurs 



At 12-13 kilometres. The cutting between Periperi and Olaria. 



At 73-74 kilometres. The Pitanga cutting, between Matta and 

 Pitanga Stations. 



At 82 kilometres. At Pojuca Station. 



At 84-5 kilometres. At San Thiago (Sao Jago), about six kilo- 

 metres from the Pojuca Station. 



Pig. 5 shows an internal cast with delicate radiating marks, due 

 to the decomposition of the^ test and its outer layer. 



There seems to be a still more truly oblong variety of this species. 

 Pig. 7. 



§ XII. OSTRACODA. 



A number of small valves occur in the same soft brownish shale 

 in a cutting at 83 kiloms. between the Station of Pojuca aniT San 

 Thiago, on the railroad from Bahia, that yields JSstlieria Mawsoni, 

 JEstheriina expansa, and ^. astartoides. They lie crowded on some 

 of the bed-planes, and are much obscured by the matrix and 

 imbed ment. 



In Plate XI the most recognizable forms are depicted (Figs. 8-14) ; 

 but it is difficult to define their characteristics. Figs._^8 and 9 may 

 belong to an oblong form of Cythere ; so also Fig. 14, but this is 

 small and nearly oval. Figs. 10 and 11 may be subtrigonal CytJiercB 

 or CytheridecB, with the anterior hinge sufficiently strong to influence 

 the outline of the valve. So also Fig. 13, but this valve has on its 

 surface local depressions, which may possibly be indicative of the 

 undulated or constricted valve of a Metacypris : see Gbol. Mag. 1886, 

 pp. 145-8, PI. IV, Figs. 1-3 ; and ibid., 1893, pp. 385-91, PL XV, 

 Figs. 1-3. Fig. 12 may be a Candona or a Cypris. 



The general aspect of the Ostracoda is that of a group of probably 

 brackish -water forms, agreeing therein with the associated Estherian 

 phyllopods. Compare the analogous Brazilian specimens treated 

 of in the Quart. Journ. Geol. Soc, vol. xvi (1860), pp. 266-7, 

 pl. xvi, figs. 13-17. 



§ XIII. Conclusion. 



It is difficult to determine if the groups of fossil Entomostraca 

 above described, represent the brackish-water conditions that 

 obtained in the late Triassic (Khsetic) or the Jurassic and early 

 Cretaceous (Wealden) times. The plant-remains of Mendoza appear 

 to be of Ehsetic age. The railway-cuttings in Brazil have not 

 yielded any definite plant- remains; and their fossil shells have 



