356 BIOLOGY OF THE PROTOZOA 



the chambers into subchambers; a single mouth present only in 

 the initial chambers; in later chambers a large number of so-called 

 mouth-pores are present. 



Genera: Group A: Calcareous; imperforate. ArcJiiacina, 

 Meun.-Chalm. ; Oi'bitolites, Link. ; Orbiculina, Lam. Group 

 B: Calcareous; perforate. Orbitoides, d'Orb. (fossil only). 



Order IV. Textulinida = Textulinidia, Rhumbler. 



Polythalamous with initial chamber without neck and succeeding 

 chambers arranged in two or more alternating rows which, in more 

 complex forms, are spirally wound. The shell material is lime, or 

 lime with sand, or sand, and the walls are usually perforate, rarely 

 imperforate. 



Family 7. Textulinidae, Rhumbler.— With the characters of the 

 group. 



Genera: Textularia, Defr.; Cribrostomum, Moeller; Bolivina, 

 Orb.; Verneuilina, Orb. (with three rows) ; and Cassidulina, 

 Orb. 



Order V. Rotalida, Brady em. Rhumbler = Rotaliaridia. 



Polythalamous with initial chamber without neck, the succeeding 

 chambers forming a fiat spiral or with a portion developed as a 

 turbo-spiral. Li some cases with an irregular heap of terminal 

 chambers (acerval) . 



Family 8. Trochamminidse, Rhumbler.— Shell material sand, sand 

 and lime or pure lime; no dimension of single chambers relatively 

 long. 



Genera: Endothyra (Carboniferous), Philips; Haplophracimimn, 

 Reuss; Trochammina, Jon. and Park.; Carterina, Brady; 

 (here the shell is made up of calcareous plates cemented 

 together in the form of a mosaic) ; Cydamrmna, Brady. 

 Family 9. Fusilinidse, Rhumbler.— Shells imperforate, with cham- 

 bers much elongate in the direction of the turns and divided into 

 numerous subchambers. Only fossil forms known. Fusidina, 

 Fischer; Schwagerina, Moeller; Schellwienia, Staff and Wedek. 



Family 10. Rotaliidse, Brady em. Rhumbler.— Calcareous and 

 invariably perforate. Spirals are so wound that either all chambers 

 are visible on the upper surface but only the last chamber from the 

 under side, or only the last chamber is visible from either side. The 

 more complex forms are provided with a canal system. 



Genera: Truncatulina, Orb.; Pukimdina, Jon. and Park.; 

 Rotalia, Lamarck; Di.sY-orbina, J. and P.; Poly f re ma, Risso; 

 Tinoporus, Montf. The Globigerina group includes pel- 

 agic or floating forms with swollen chambers which start 

 with spiral arrangement but become irregular; usually 



