52 THE ENTOMOSTRACA OF 



in a new sub-genus, Cytherideis (see p. 46) ; for instance, C. angusta, ' Monog. Cret. 

 Entom.' pi. 6, fig. 18. 



Amono-st the " Bairdise" of Bosquet, Reuss, and Bornemann, there are, I believe, 

 included several species both of Cytlieridea and Cytherideis. 



No. 1. Bairdia subdeltoidea, Miimter, sp. Plate IV, figs. 2 a, 2 (5, 3 ; PI. VI, 



figs. \a,\ b,2. 



Cytheke SUBDELTOIDEA, i¥aw«<er. Jabrb. f. Min., &c., 1830, p. 64; Neues Jabrb. f. 



Miu., &c., 1835, p. 446. 

 Cytherina subdeltoidea, F. a. Roemer. Ibid., 1838, p. 517, t. 6, fig. 16. 



— — Hauer. Ibid., 1839, p. 429. 



— F. A. Roemer. Verstein. Nordd. Kreid., p. 105, t. 16, fig. 22. 



— Geinitz. Charact. Sacbs.-Bobm. Kreid., 3 Abtb., p. 64. 



_ _ lb. Grund. Verstein., p. 244, t. 8, fig. 21. 



— Reuss. Verstein. Bohm. Kreid., 1 Abth., p. 16, t. 5, fig. 38 ; 



and 2 Abtb., p. 104. 



— lb. Haidinger's AbhandL, iii, p. 49, t. 8, fig. 1. 



_ — lb. Ibid., iv, p. 4 7. 



— lb. Apud Geinitz, Quadersandst. oder Kreid. Deutsch, p. 98, 



No. 10. 



— — Eichwald. Letbaea Rossica, t. 11, fig. 23. 



— Naumann. Lehrb. Geogn., 2. Halfte, t. 60, fig. 24. 



— trigona, Bosquet. Mem. Soc. Roy. Liege, iv, p. 358, t. 1, fig. 3. 

 Bairdia subdeltoidea, lb. Mem. Gouron. Acad. Belg., xxiv, p. 29, t. 1, fig. 13. 

 Cythere (Bairdia) subdeltoidea, Jones. Monog. Entom. Cret., p. 23, t. 5, fig. 15. 



— — — Reuss. Denkschrift. d. Akad. Wiss. Wien., vii, pp. 41, 



139. 



INCH. 



Length, -^ -^^ -^^ Recent : Britain ; West Indies ; Mauritius ; Manilla ; Australia. 



Tertiary : Britain ; Europe ; Virginia. 

 Cretaceous : Britain ; Europe. 



Carapace triangular, gibbous, acute at the extremities, smooth or setiferous and 

 sometimes finely punctate ; right valve smaller and more angular than the left. [For 

 a fuller description of the valves, see ' Monog. Entom. Cret. Form.,' p. 23.J 



Cijthere {Bairdia) subdeltoidea is a common form in the Tertiary deposits throughout 

 Europe ; it is plentiful in the Tropical Seas,'' and occurs also on the British coasts.^ 



' The -B. subdeltoidea of Australia is punctate, and has the rosette-like lucid spots of the Cbalk form 

 of this species ; that of Turk's Island, Bahamas, more resembles the Crag form both in its globosity and in 

 the less compactness of the spots. 



- The B. subdeltoidea of Arran, here referred to, is evidently a variety, being narrow and presenting a 

 difference in the arrangement of its lucid spots. 



