38 SYNOPTIC COLLECTION. 



into the Orbulina that possesses Globigerina characters 

 in youth and loses them in age. 



In PI. 38, figs. 1,2, Hastigerina murrayi Wy. T., which 

 belongs to the Globigerina group, is represented. The 

 shell is thin and possesses spines (fig. i). The proto- 

 plasm of the living animal envelops the shell, taking the 

 peculiar form of bubble-like extensions, and thrown out- 

 ward beyond these are the extremely long pseudopodia 



(fig- 2). 



The group of Nummulitidae is the most differentiated 

 of the Foraminifera. The mounted specimen No. 39, 

 Fusilina, is exclusively fossil. The shell is bilaterally 

 symmetrical. The chambers extend from one end of the 

 shell to the other, and each convolution encloses the pre- 

 vious whorl. The walls of the chambers are usually single, 

 and there are no interseptal canals. 



Nummulites is represented in the Collection by speci- 

 mens (Nos. 40, 41). No. 40 shows two whole shells, and 

 between these a horizontal and a vertical section ; back 

 of these single specimens are two pieces of Nummulitic 

 limestone ; one showing fresh surfaces, while the other 

 has been weathered by the action of the carbon dioxide 

 and moisture in the air so that the shells stand out more 

 prominently. No. 41 is remarkable for its size, being a 

 giant of its kind. The internal structure is shown in PI. 

 42. The figure at the left is a horizontal section of 

 Nummulites granules a d'Arch., showing the double walls 

 between the chambers and the canal system. The two 

 central figures are Nummulites laevigata Lam.; one the 

 whole shell and the other a vertical section showing 

 chambers and walls. The figure at the right is Num- 

 mulites mamillata d'Arch., with a portion of the outer 

 shell removed. 



