200 FAMILY GLOBIGERINIDA. 



343. Such was the nomenclature of the group when it was first taken up by D'Orbigny ; 

 who, in his first systematic arrangement of the Foraminifera (lxix) created, in addition to 

 Rotalia, the genera G yroidina , Planorbulina, TruncatuUna, Anomalbm, RomUna, CaJcarina, and 

 Turhinolina ; to which he subsequently added Asterlgerina (lxxi), whilst he abandoned Gyroidlna 

 as not sufficiently differentiated from Rotalia, and Turhinolina as not sufficiently differentiated 

 from Bosalina. To these the genus Siphonia has been added by Reuss (lxxxvix) ; and the 

 genus Jcervulina by Schultze (xcvii). — On the other hand, by Prof. Williamson (ex) the genera 

 Boialina and Rosalina have been reunited, for the excellent reason that tlieir distinctive 

 characters are such as a mere difference of age suffices to destroy ; and he further correctly 

 stated that (as had been in some degree divined by M. D'Orbigny himself) certain shells 

 ranked by D'Orbigny under the genus FalvuHna are true Rotalines. 



344. The Rotaline type has been specially studied by Messrs. Parker and Rupert Jones, 

 ■who have found it requisite to throw together again all the genera Rotalia, Planorbulina, 

 TruncatuUna, Rosalina, Asterigerina, Anomalina, Planulina, and Calcarina of D'Orbigny, together 

 with several species of his Valvulina, as well as the Siphonia of Reuss, and the Acervulina 

 of Schultze ; and to rearrange the resultant aggregate of forms upon entirely new principles 

 under six genera, — viz., Rotalia, Calcarina, Planorbulina, Puloinulina, Discorbina, and Cymba- 

 lopora ; for the first three of which they employ the names previously given by D'Orbigny, 

 but in a different sense. Regarding Rotalia Beccarii as the type of the true Rotalia, and 

 Calcarina Sjioiyleri as the type of the true Calcarina, they arrange under those genera respec- 

 tively such forms as correspond with their types in all essential particulars ; and thus it comes 

 to pass that the Rotalia of Messrs. Parker and Rupert Jones corresponds with parts of 

 the Rotalia, Bosalina, Gyroidina, Asterirjerina, and Calcarina of D'Orbigny ; whilst their 

 Calcarina includes part of the Rotalia of D'Orbigny with part of his Calcarina. The Planor- 

 bulina of Messrs. Parker and Rupert Jones has a scope very different from the Planorbulina 

 of D'Orbigny ; for it reunites parts of D'Orbigny's Rotalia, Rosalina, and Anomalina, together 

 with TruncatuUna, Planulina, and Acervulina (Schultze), to part of D'Orbigny's Planorbulina. 

 The genus Pulvinidina, of which the type is the Rotalia repanda (the Pulvinulus rcpandiis of 

 Lamarck), includes parts of the genera Rotalia, Planorbulina, and Valvulina of D'Orbigny ; and 

 in like manner the genus Biscorbina, of which the type is the Rotalia turbo (of which one 

 variety had been named Biscorbites vesicularis by Lamarck), is made up of parts of the genera 

 Rotalia, Rosalina, Valvulina, Asterigerina, Anomalina, and Globigerina of D'Orbigny. Lastly, 

 the genus Cymbalopora consists of a small group of very peculiar forms which had been 

 included by D'Orbigny in his genus Rosalina. 



345. The typical genera of the Rotaline series are those in which the shell essentially 

 consists of a succession of coarsely porous or Globigerine segments, arranged in a turbinoid 

 spire, and communicating with each other by a cresentic aperture situated at the janction of 

 the septal plane with the free surface of the convolution. The pores (Plate XIII, fig. 1), 

 in characteristic examples of the Rotahne series, are from l-2000th to l-5000th of an inch 

 in diameter ; they are usually larger on the external surface than on the internal, as is 

 shown by sections which traverse the thickness of the shell (fig. \, b); and it very commonly 

 happens that each external orifice lies at the bottom of a sort of funnel that is formed by a 



