SILURIAN OSTRACODA PROM NORTH AMERICA, ETC. 539 



lip along the free border of the valve, bearing a thin, flange-like, 

 projecting border, either narrow or broad, and either plain or marked 

 with radiate striae. In other respects the valves are Primitian in 

 shape and ornament*. 



6. EuRYCHiLiNA RETICULATA, TJlrich. (PI. XX. figs. 13 a, 13 6.) 



Eurychilina reticulata^ Ulrich, Contributions, &c., Part II., 1889, 

 p. b2, pl. 9, figs. 9 & 9 a. 



mm. 



Length, including the fringe 3-5 



, without the fringe 2*5 



Height, with the fringe 2 



, without the fringe 1| 



An inner (fig. 13 a) and an outer cast (fig. 13 h) of one fine indi- 

 vidual belonging to this handsome species, in the decomposed Chert 

 of the Corniferous (Devonian) Limestone of Ontario Co., New- York 

 State, supply material for the recognition of the same form as is 

 figured and described by Mr. E. 0. Ulrich, as quoted above, from 

 ^' the Trenton Shales at Minneapolis, St. Paul, Fountain, and other 

 localities in Minnesota." The recurrence of this beautiful species 

 in the Devonian Formation is of great interest. 



Another fringed Ostracode, having the Primitian features of um- 

 bilical pit and furrow, and a reticulate sculpture, is the Sardinian 

 '•^ Beyrichia reticulata,'^ oi J. G. Bornemannf. Though imperfect, 

 the specimen has evidently been carefully figured ; and it is 

 reproduced here for comparison (PI. XX. figs. 14 «, 14&), because 

 the work is rare. There is not, however, sufiicient evidence in 

 the drawings that the ventral border had the inner thickened 

 marginal lip or rim that Eurychilina requires. Should, however, 

 Dr. Bornemann's prove ultimately to belong to this genus, the spe- 

 cific name of Mr. IJlrich's species will have to be changed. 



* For some Beyrichian forms, with thickened and frilled edge, and regarded 

 as Beyrichiopsia by Jones & Kirkby, see 'Geol. Mag,' 1886, p. 433, &c. pis. 11 

 & 12 ; and others still retained in Beyrichia are noticed in ' Ann. & Mag. Nat. 

 Hist.' ser. 5, vol. xiii. 1886, p. 257, pl. viii. figs. 1 & 2. Dr. Aurel Krause has 

 described some flanged and fringed Frimitics, and a fringed Entomis, in his 

 Memoir on the Beyrichice and related Ostracoda from the Lower-Silurian Drift- 

 gravel of North Germany, 'Zeitsch. d. D. geol. Ges.' 1889, pp. 1-26, pis. 1 & 2. 

 Without sections of the ventral border, to show the proportions of the thick- 

 ened marginal rim and flange, it is impossible to determine how far any of 

 these may agree with Mr. Ulrich's diagnosis of Eurychilina. Fig. 3 i in Dr. 

 Krause's plate, referred to, does not exhibit the required thickness of lip, being 

 only the surface-outline of one valve of Prlmitia distans, Kr., which is curiously 

 like Bornemann's ''Beyrichia reticulata" allowing for the effect of pressure on 

 the latter (PL XX. figs. 14 a, 146). 



t ' Paleoncologie de I'ile de Sardaigue,' par le Prof. Chev. Joseph. Mene- 

 ghini, Turin, 1860 ; Supplement (p. 8). ' Voyage en Sardaigne,' &c. par Lieut.- 

 General Conte Albert De la Marmora, 3eme Partie, Geologic, vol. ii. Lettre 

 de M. le Docteur J. G. Bornemann (p. 7), relating to fossils found in schis- 

 tose Silurian rocks at a spot called Perdas de Fogu, near the village of Flumi- 

 nimaggiore, Province of Cagiiari, in the Island of Sardinia ; collected and de- 

 scribed by Dr. J. G. Bornemann. 



Q. J. G. S. No. 184. 2 k 



