134 PROF. W. C. WILLIAMSON CORRECTIONS OF 



References to the Memoir. Modern Nomenclature. 

 Plate II. 



f.28. Bosalina globidaris, D'Orb., or. More mSL t ure & Planorbulina mc- 



Botalia stigma, Ehr., older (pp. dit erranensis. 



38-43) i 



29. Decalcified animal of the same. 



In reasoning upon this specimen in the memoir (pages 

 38-39) , I erroneously concluded that the form which it 

 assumed afforded proof that its external surface consisted 

 of a membrane more dense than the rest of the structure. 

 I first became convinced that my reasoning was inaccurate 

 from observing that some collodion dried up in a bottle in 

 precisely the same way as the gelatinous sarcode of the 

 Foraminifer dried up within the interior of each segment 

 of the shell ; i. e. it first shrank considerably in size, its 

 external surface assuming a hard membranous aspect, after 

 which the contraction ceased in the centripetal direction. 

 The soft contained collodion now contracted from within 

 outwards upon the hardened exterior, which ultimately 

 assumed the form and aspect of a dense membrane en- 

 closing a hollow cavity. This is precisely what we see in 

 these dried-up Foraminifera. 



fig. 30. Polystomella (p. 44) ( P ^ stomdla striatopunctata 



6 * U ' I (Fichtel & Moll). 



31. Peneroplis (p. 44) Peneroplis pertusus, Forskal. 



This is the species so widely known as P. planatus, the 

 specific name given to it by Fichtel and Moll. 



f. 32. Peneroplis, young shell (p. 45) Peneroplis pertusus. 



33. Textilaria (p. 47) Bolivina punctata, D'Orb. 



34. Foraminifer (p. 45) { ^piriUina perforata (William- 



I son). 

 Plate III. 

 f. 35. Truncatulina tuberculata (p. 46) . . . Truncatulina lobatula. 



36. Spiroculina(p.46) f ^ing very young examples, it is 



„ r . . I almost impossible to deter- 



oo' t>-7 7- / i/V' mine the species of these three 



3o. Biloculina (p. 4b) _,.,. 7 L 



39. Lagena globosa ? (p. 47) Lagena globosa (Montagu). 



