the Palceozoic Bwalved Entomostraca^ 55 



Malverns and elsewhere, described in the ^ Annals Nat. Hist.'* 

 ser. 3. vol. xvi. (1865), pp. 414-425, pi. 13, we have a clearer 

 view of the probable relationship of some of these specimens 

 from Kildare; whilst others of them fall into the groups of 

 Cythere and Bairdia^ as recognized by the shape of the cara- 

 pace-valves. Primitia is a characteristically Silurian genus f 

 (see Ann. Nat. Hist. ?. c.) ; and now Cythere and Bairdia are 

 shown to have existed at that early period, judging from fossil 

 carapaces, such as already have been accepted as evidence of 

 the persistency of these genera from the Upper-Palaeozoic 

 (Carboniferous) times to the present day. 



1. Primitia MaccoyiiX^ Salter, sp. PI. VII. figs. 1 a-c, 



2 a&h^ 3 a-e, 



Cythere phaseolus, M^Coy (not of Hisinger), Synops. Sil. Foss. Ireland, 



1846, p. 58. 

 Cythere Maccoyii, Salter, in Morris's Catal. Brit. Foss. 2nd edit. 1854, 



p. 105. 

 Cythere Maccoyii^ (" Forbes, n. s. ?"), Baily, Descript. Quarter-Sheet 



35 N.E. Geol. Surv. Ireland; 1858, p. 10. 

 CytJiere? phaseolus^ (M'Coy, not of Hisinger), Salter, in Murchison's 



'SHuria,' 2nd edit. 1859, p. 638, and 3rd edit. 1867, p. 617. 



Carapace like a bean, smooth, subovate, swollen in the 

 middle and equally compressed at the ends ; somewhat Leper- 

 ditioid in outline, having a nearly straight dorsal line and 

 slightly sloping antero- and postero-dorsal margins, and being 

 somewhat narrower at one extremity than at the other. Dorsal 

 profile acute-oval (in some specimens rather acute-ovate). At 

 the middle third of the hinge-line the edge of each valve is 

 suddenly depressed, and the boundary of the inflection is 

 rounded in the young and slightly ridged in the old specimens. 

 The ventral border of each valve is thickened with a rim, 

 wliich is doubled in large and aged individuals. 



* In this paper on Primitice, at p. 417, the name ^' Schrenk " is twice 

 printed by mistake for Schmidt ; also in the footnote at p. 424. 



t To the already recorded Primitice (Ann. Nat. Hist. I. c.) we wish to 

 add two, namely, (1) Cytheropsis rugosa, Jones (Ann. Nat. Hist. ser. 3. 

 vol. i. p. 249, pi. 10. fig. 5, figured upside down) from the Trenton Lime- 

 stone of Canada, which in shape much resembles Primitia semicircularis, 

 J. & H., whilst its punctation is such as we see in P. variolata, ,1. & H. ; 

 (2) Leper ditia Sohsnsis, Jones, a very small Leperditioid Entomostracan, 

 without eye-tubercle or muscle-spot, from the Lower Lingula-flags, of 

 Upper Solva, on the west side of Solva Harbour, near St. David's, South 

 Wales (see Annals Nat. Hist. ser. 2. vol. xvii. p. 95, pi. 7. fig. 16 ; and 

 Quart. Journ. Geol. Soc. vol. xx. p. 238). 



X For the relative sizes of the Primitice &c. described in this paper, see 

 further on, page 58. 



§ Specimens from the Chair of Kildare are also referred to, in the 

 'Catal. Collect. Fossils Mus. Pract. Geol.' 1865, p. 7, as " Cythere pham)- 

 lus, case 7, tablet 37, specimen 15." 



