22 PROF. T. R. JONES ON SOME PALiEOZOIC OSTRACODA 



Both specimens are from the Hamilton Group, at Monteith's 

 Point, Canandaigua, State of New York. 



2. ISOCHILINA (?) FABACEA, Sp. nOV. (PI. II. fig. 11.) 



Size: length -92 mm., height '44 mm. 



Narrow-oblong, bean-shaped, straight above, gently c^irved below, 

 semicircular in front, obliquely rounded behind, faintly impressed 

 in the middle of the dorsal region ; sloping gently dorsally, and 

 more abruptly on the free margins. Surface apparently punctate, 

 but in reality delicately reticulate all over. 



From the Hamilton Group, at Eighteen-mile Creek, Lake Erie 

 Shore, N.Y. 



3. IsocuiLiNA Seelti (Whitfield). (PI. I. fig. 7.) 



Primitia Seelyi^ Whitfield, ' Bulletin American Mus. Nat. Hist, 

 vol. ii. no. 2, 1889, p. 60, pi. xiii. figs. 6, 7. 



Size : length 5*0 mm., height 3*2 mm. 



The specimen here figured difi'ers somewhat from Prof. Whitfield's 

 illustration in being less Leperditioid, that is, more oblong, being as 

 high in front as behind, in having a more developed posterior 

 cardinal angle, in not showing a smooth space in the antero-dorsal 

 region, and in having a slight swelling (with a faint depression) on 

 the median line behind the centre. Its ventral margin is that of 

 an IsocJiilina. I cannot refer it to Primitia. One of its nearest 

 allies is IsocJiilina lahrosa, Jones, Ann. & Mag. N. H., May 1889, 

 pp. 383, 384, figs. 3 and 4, and pi. xvii. fig. 11 ; and another, but 

 not so near, is IsocJiilina Jonesi, Wetherby, ' Journ. Cinciiin. Soc. 

 Nat. Hist.' vol. iv. 1881, p. 4 (separate), pi. ii. figs. 7, 7 a. 



Erom a dark blue limestone, Shoreham, Vermont, and waterworn 

 fragments of a granular limestone. Providence Island, Lake Champ- 

 lain : probably Birds-eye Limestone. Our figured specimen is in 

 grey limestone largely composed of IsocJiilinoi (Providence Island). 



4. IsocHiLiNA GEEGARiA (Whitfield). (PI. I. figs. 9, 10.) 



Primitia gregaria, Whitfield, ' Bulletin N. H. Mus. N. Y.' vol. ii. 

 no. 2, 1889, p. 58, pL xiii. figs. 3-5. 



Length. Height, 

 mm. mm. 



Si,eJ^ig- 9 2-9 2-06 



^^''^ [ 10 2-6 1-8 



This species is variable in outline and features, as noticed by 

 Prof. Whitfield. Eig. 10 agrees in outline with Prof. Whitfield's 

 fig. 5, but the aspect of the nuchal notch and its tubercles approaches 

 that of his fig. 3. Our fig. 9 differs from all in outline and notch ; 

 but, as to the latter feature, it approaches fig. 5, one tubercle lying 

 in a broad notch. The furrowed sides of the notch in our fig. 10 

 remind us of a complex furrow on the front slope of a Carboniferous 

 Cyclus, sp., having lumpy margins, and of the ocular spot and its 



