PLATE VI. 



With the exception of the last eight Figures, ^vhich represent different forms of Lituola, this Plate is devoted to a 

 series of illustrations of the principal varieties of the Milioliiie type. 



Fig. 

 1.- 



.3.- 



4.— 



6.— I 



7.- 

 8- 



13.— 



14.- 



15.- 

 16- 



19- 



34.- 

 35.- 

 36.- 



-Lateral view oi -a Spiroloculina, of nearly circular 

 outline and almost continuously spiral mode 

 of growth. 



-Similar view of a Spiroloculina, of very elongated 

 form and narrow aperture. 



-Similar view of an elongated Quimjuelocu ina 

 with longitudinally furrowed surface. 



Similar view of a more rounded Quinqueloculina, 

 ■with longitudinally furrowed surface. 



Similar view of a QuinquelociiUna, with strong 

 transverse plications. 



Similar view of a Quinqueloculina, whose exterior 

 is arenaceous. 



-Front view of a BUocuVuia, with smooth surface. 



12. — Outline views of BilocuUiKe, to show the 

 variety in the forms of their apertures. (After 

 D'Orbigny.) 



■Lateral view of TrilocuUna, with strong, super- 

 ficial reticulation. 



—Lateral view of TrilocuUna, whose surface is in- 

 dented by minute pits. 



-End view of CiucilocuUna. (After D'Orbigny.) 



-18. — Apertures of Spirolondina and TrilocuUna, 

 showing three stages in the development of 

 the lingula. 



-32. — Apertures of different specimens, and of 

 different parts of the same specimens, of a 

 Targe Biloculina from the Philippines, which 

 is represented with the last chamber laid open 

 in Fig. 33. 



—Section of Hauerina, through the median plane. 



— Lateral view of a deeply plicated Hauerina. 



— A, Lateral view of Hauerina ; b, its cribriform 

 aperture. 



Fig. 



37. — A, Lateral view of Fabiilaria, with its surface 

 abraded in parts, so as to lay open the passages 

 immediately beneath ; b, end view, showing 

 its cribriform aperture. 



38. — Transverse section of Fabularia, showing its 

 general biloculine plan of growth (the cham- 

 bers at the opposite sides meeting each other 

 along the line a, b), and the occupation of the 

 principal part of its chambers with solid shell- 

 substance, which is channelled out by inos- 

 culating passages ; a' , portion of this section 

 more enlarged, showing the junction along 

 the Hue a, b of the interior tuberculated wall 

 of oue chamber with the external pitted wall 

 of the preceding; a, a small portion of the 

 internal layer, showing the minute tubercles 

 projecting from its surface ; b, a small portion 

 of the external layer, showing the pits of its 

 internal surface, into which the tubercles of 

 the subjacent layer are received. 



39, 40. — Lateral and front views of Lituula canariensis 

 [Nonionina Jeffrcysii, Will.) 



41. — Portion of the shell of the same, highly magnified, 

 to show the manner in which it is made up of 

 agglutinated grains of saud. 



42. — Portion of the shell of Lituola Soldanii, highly 

 magnified, sho^Ting the larger arenaceous par- 

 ticles to be imbedded in a cement composed 

 of amorphous particles united by an adhesive 

 exudation. 



43. — Lituola Soldanii. 



44. — Lituola nautiloidea ; a, lateral aspect, showing 

 the interior partly laid open by attrition ; b, 

 septal plane. 



45. — Septal plane of another variety of the same. 



40. — Another variety of the same. 



