EXPLANATION OF PLATES. 



Plate XVI. 



Descrdtios of Figures. 



Fio. Page 



1. Orhiculiiva adunca (F. and M.). Xormal type, showing sub-di\-ision 



of chambers into chamberlets by transverse septa, . . .159 



2. Orbiculina adunca (F. and M.). Peneropline variety, showing un- 



di\nded chambers, with thickened septal walls, . . . 159 



3. Abnormal variation. A specimen combining the characters of the 



genera Textularia and Globigerina, 161 



4. Abnormal variation. A specimen combining the characters of the 



genera Miliolina, Comuspira, and Opthalmidium, . .161 



5. Massilina secatis (d'Orb.). Abnormal twinned specimen, with 



chitinous test and produced nubecularine tube. . . .164 

 (For fig. 6, see Plate XVIL) 



7. Vemcuilina polystropha (Reoss). Initial chambers of a megalo- 



spheric specimen viewed as a transparent object, . . .171 



8. VtmetiUina polystropha (Reuss). Megalosphere, sub-divided by 



internal chitinous septum, 171 



(For fig. 9, see Plate XVIL) 



10. VemeuUina polystropha (Reuss). Initial chambers of a micro- 



spheric specimen Niewed as a transparent object, . . 172 



11. VemeuUina pusUla, Goes. Long form >iewed as a transparent 



olyect 173 



(For fig. 12 (t s<q.. see Plate XVIL) 

 36., 

 37. 

 38. 

 39. 

 40. 

 41. 

 42. 

 43. 



44. ^fnsgil\na secans (d'Orb.). Abnormal tank-grown specimen, with 



terminal articuline chambers and supplementary orifice, . 176 



Massilina secant (d'Orb.). Tank-grown specimens exhibiting 



various abnormalities in growth, 176 



