18 PROF. T. R. JONES OX SOME PALJSOZOIC OSTRACODA 



8. Beyrichia jequilatera, Hall. (PI. II. fioj. 6.) 



Beyrichia eqiiilatera, Hall, ' Canadian Nafc. & GeoL' vol. v. 1860, 

 p. 158, fig. 20. 



Beyrichia equilatera, Dawson, 'Acadian Geology,' 3rd edit. 1878, 

 p. 609, fig. 217. 



Size : length '8 mm., height '52 mm. 



The specimen shown by fig. 6 is a poor cast of a Beifricliia. related 

 to Beyrichia KJoedeni. It is from Arisaig, Nova Scotia, in the 

 same kind of sandstone as that containing B. pustulosa (see below). 

 It is labelled B. equilatera, bnt is not much like the figure published 

 in the ' Canadian Naturalist and Geologist/ 1860, which seems to 

 have one strong curved ridge, a small central lobe, and two little 

 lobes (not mentioned in the description) representing a third ridge. 

 Our figured specimen has the third lobe slightly modified by a faint 

 oblique sulcus, but is not actually divided. The anterior ridge at 

 the other end rises high up dorsally, and curves well down to join 

 the middle lobe. 



9. Beyrichia tfberculata, Boll, var. pustulosa, Hall. (PI. II. 

 figs. 1 a, b, c.) 



Beyrichia pustulosa, Hall, ' Canad. Nat. & Geol.' vol. v. 1860, p. 157, 

 fig. 19 ; Dawson, 'Acad. GeoL' 2nd edit. 1868, & 3rd edit. 1878, 

 pp. 608, 609, fig. 216. 



Beyrichia tuherculata^ Jones, ' Quart. Journ. Geol. Soc' vol. xxvi. 

 1870, p. 492 ; ' Geol. Mag.' 1881, p. 344, pi. x. figs. 8, 9, & 10. 



Size: length 5 (?) mm., height 2*8 mm., thickness of carapace 

 2 mm. 



Our fig. 1 is one of the forms of this Nova-Scotian Beyrichia, and 

 being an internal cast is comparable with fig. 8, pi. x. Geol. Mag. 188 1 ; 

 but it has lost its anterior fourth by fracture, and the hypertrophy 

 of the antero-ventral lobe makes a difference. Although the hinder 

 lobe in fig. 8 (Geol. Mag.) is partly broken away, thetwo s])ecimens 

 may have agreed in this region. As for the valve itself, fig. 9 

 (Geol. Mag.) is quite equivalent to the cast shown in fig. 8 and to 

 our specimen, except that the latter has the hjpertrophied lobe, 

 which, however, is not at all an essential or specific feature *. 



Our fig. 1, if restored with its valve complete, may be regarded 

 as equivalent to Boll's B. tuherculata, having the large lobe, fio'. 1 a 

 (Archiv Ver. Fr. Nat. Meklenburg, 16 Jahrg., 1862, p. 119). ^This 

 form, and the same without the big lobe, are described and figured 

 by G. Beuter (Zeitschr. d. D. g. Ges. vol. xxxvii. 1885, p. 634, 

 pi. XXV. figs. 2a & 2 b) as -5. tuherculata-gilhosa. Pig. 10 (Geol. 

 Mag.) is not quite perfect along the antero-dorsal margin ; but may 

 be regarded as a large growth of B. tuherculata, with the lower 

 portion (preserved) of the anterior lobe proportionally and normally 

 large. 



* Ann. & Mag. N. H., April 1886, pp. 339-342. 



