218 Messrs. Parker and Jones on 



Poly cystines (under the term "siliceous Infusoria"), shell- 

 prisms, echinoclermatal plates, &c. Secondly, he gives valua- 

 ble notes on their distribution in the Levant, on the British 

 coasts, in the West Indies, and elsewhere. Thirdly, their 

 occurrence in the fossil strata of Barbadoes, Sicily, Paris, 

 North and South America, and especially in the Chalk of 

 Kent (Mr. Harris's collection), Yorkshire, Antrim, &c., the 

 limestone of Lebanon, the Speeton Clay, Oolites, Lias, and 

 the Mountain-limestone, with careful references to the labours 

 of others, especially Ehrenberg and D'Orbigny, Fourthly, 

 the origin of limestones, the manifold changes they have suf- 

 fered, and silicification are his special objects of study ; and, 

 though doubtless Foraminifera are found to be the chief 

 material of many limestones of very different ages, he warns 

 his readers to be cautious in using these low and simple 

 animalcules as exact criteria either for climates, depths, and 

 regions, or for chronological succession. He critically applies 

 the researches and statements of both Ehrenberg and D'Or- 

 bigny in support of this well-founded caution. Since 1847 

 few have laboured more than Williamson himself in clearing 

 away the obscurities that beset the Foraminifera, enabling us 

 to understand their genera, species, and varieties, to trace 

 them through their species-life, and to compare them from 

 remote strata and distant seas — and this with improved know- 

 ledge and far better results than fell to the lot of earlier 

 observers. 



We here refer the student to some careful drawings of 

 Foraminifera from the Pacific, seen by transmitted Jight^ and 

 engraved in a former volume of the ' Ann. & Mag. Nat. Hist.' 

 for comparison with those given by Ehrenberg. Among them 

 are several of the species met with in the ' Mikrogeologie.' 

 We have to correct the nomenclature used by the author. 



J. D. Macdonald, " On Foraminifera from the Feejee Islands." 

 (Ann. Nat. Hist. ser. 2. vol. xx. pp. 193 &c. 1857.) 



PI. 5. figs. 1, 2. Doubtful. Figs. -3-5. Polycystlna. From 1020 



fathoms, 

 fig. 6. Uvigerina pygmaea, UOrh. Dimorphous variety. \ From 

 figs. 7-10. Lagena globosa et marginata {^Montagu). > 440 



Entosolenian. j fath. 



figs. 11-14. Globigerina buUoides, D'0?'b. ~\ 



fig. 15. Planulina? 

 fig. 16. Cymbalopora Poeyi {UOrh.). 

 fig. 17. Discorbina globularis? (D'0r6.). Young, 

 figs. 18, 19. Nonionina umbilicatula {Montagu). 

 fig. 20. Discorbina globiilaris ? {D'Orb.). J 



I From 



yi020 



fath. 



