70 Miscellaneous, 



led me to interpret the facts observed in a manner quite different 

 from that which had been regarded as admissible. In examining 

 the sands from a deep dredging (4255 metres) executed by the 

 ' Talisman ' at the Canaries, I found a great number of OrbuUnce of 

 all sizes, and so clean that when soaked in chloroform and immersed 

 in Caoada balsam they became perfectly transparent. It is then 

 observed that among the smallest of only 320 /^ in diameter, and 

 those of medium size, some are empty, while others have their cavity 

 occupied entirely or in part by a succession of globular chambers 

 arranged in a trochiform spire, like those of certain Glohiyerince. 

 The large Orhidince, attaining nearly 1 millim. in diameter, are 

 almost always empty. 



These interior chambers are more easily distinguished after the 

 removal of a portion of the Orhulina, or when entirely separated 

 from their envelope. We then find that their exceedingly deUcate 

 plasmostracum is pierced by distant perforations ; the chambers of 

 the first two turns of the spire are smooth ; the following chambers 

 boar fine scattered spines, which, upon the last ones, are prolonged 

 to the inner wall of the Orhulina, to which they attach themselves*. 

 These chambers communicate with each other and with the interior 

 of the Orhulina by a small semilunar aperture, situated below and 

 opposite to (he turn of the spire. In the largest Orhulince the spire 

 does not include at the outside more than sixteen chambers. 



Now all Glohigerino', as Carpenter points out, even when young, 

 have a comparatively thick plasmostracum, very closely placed per- 

 forations, one or several apertures widely invading the chambers, 

 and a rugose exterior, in conse(iuence of the great number of spines 

 which cover its surface. Hence between the interior chambers of 

 the Orhulince and the Globigerince there is only a resemblance of 

 form. 



On the other hand, we find many small Orhulime in which the 

 last or last two interior chambers form projections upon the sphere; 

 but then these protuberances are surrounded by a i)lasmostracum 

 as thick as the rest of the envelope. The interior chambers there- 

 fore do not quit the Orhulina ; further, if they did so we ought 

 never to meet with large empty Orhulince. 



From these facts we can draw only one logical conclusion, nameh% 

 that we have before us a case of dimorphism analogous to those 

 which M. Munier-Chalmas and myself have already indicated in the 

 Nummulitest, the Miliolidse J, and many other genera of perforate 

 and imperforate Foraminifera §. 



The single chamber of the Orhulina is the homologue of the 

 initial chamber of the other Foraminifera ; when it remains empty 



* This fact was observed by Pourtales. 



t Bull. Soc. Geol. Fr. ser. "3, viii. p. 300; 'Annals,' ser. 5, vol. xi. 

 p. 336. 



X Oomptes Reudus, 1883, pp. 862 and 1598 ; ' Annals/ ser. 5, vol. xii. 

 p. 67. 



§ Feuilledes jeunesNaturalistes, 14" anu^e; Congresde Rouen, p. 520 

 (1883). 



