880 Transactions of the Society. 



Spiroloculina depressa, var. cymbium, Williamson, 1858, Eec. For. Gr. 

 Br., p. 82, pi. vii. fig. 179. 

 Frequent. 



8piroloeulina excavata, d'Orbigny. 



Spiroloculina excavata, d'Orbigny, 1846, For. Foss. Vien., p. 271, pi. xvi. 



figs. 19-21. ■ 

 „ „ Brady, 1865, Nat. Hist. Trans. Northd. and 



Durham, vol. i. p. 93, pi. xii. fig. 1. 

 Widely distributed, but less common than some other species of the 

 genus. 



» MiLiOLiNA, Williamson. 



Here, as in the 'Challenger' Eeport, I have retained the generic 

 term Miliolina in the sense in which it is employed by Williamson. I 

 do not, I hope, in the least underrate the value and importance of the 

 researches of MM. Munier-Chalmas and Schlumberger on the embryology 

 of the group, but I confess I am unable, in the present state of our 

 knowledge, to see any way to the application of embryological characters 

 to a practical and convenient system of generic nomenclature. So far 

 as I understand, ib is admitted that, whilst general rules may be laid 

 down with relation to the embryological difierences of certain subordinate 

 groups, the " distinctive " features have a considerable range of variation, 

 and are in fact not much more constant than those more easily recognized 

 external peculiarities which serve as the basis of classification amongst 

 other Foraminifera. We have, however, still much to learn in the 

 matter, and everything to hope from M. Schlumberger's further investiga- 

 tions. Perhaps the difl&culty may be eventually solved by the recognition 

 of certain subgeneric types ; the d'Orbignyan genus Adelosina, for 

 example, represented in the British list by Miliolina hicornis, appears 

 to be readily distinguishable, under ordinary circumstances, by external 

 as well as internal characters. 



Miliolina trigonula, Lamarck, sp. 



Miliolites trigonula, Lamarck, 1804, Ann. du Museum., vol. v. p. 351 

 No. 3 ;— 1822, Anim. s. Vert., vol. vii. p. 612, No. 3. 



Miliolina trigonula, Williamson, 1858, Kec. For. Gt. Br., p. 84, pi. vii. 

 figs. 180-182. 

 Generally distributed. 



Miliolina tricarinata, d'Orbigny, sp. 



TriloGulina tricarinata, d'Orbigny, 1826, Ann. Sci. Nat., vol. vii. 



p. 299, No. 7 ;— Modele, No. 94. 

 „ „ Brady, 1864, Trans. Linn. Soc. Lond., vol. xxiv. 



p. 466, pi. xlviii. fig. 3. 

 Shetland (Brady, Waller) ; Estuary of the Dee (Siddall) ; Mount's 

 Bay (Millett) ; various points on the coast of Ireland (Wright, Balkwill 

 and Wright, Balkwill and Millett) ; west of Scotland (Robertson). 



