47 {43) Chambers are few (3 or 4); test is relatively thick 48 



47 (43) Chambers are many (6 or more), not inflated; test is relatively flat 49 



X150 



48 (47) Test is moderately compressed; chambers are inflated and periphery lobulate. Diameter 0.22-0.25 mm. a, 



Spiral view; b, umbilical view; c, edge view Trochammina advena 



X100 



48 (47) Test is compact, subglobular; chambers are not inflated and periphery not lobulate. Diameter 0.30-0.40 



mm. a. Spiral view; b, umbilical view; c, edge view Trochammina compacta 



49 (47) Umbilical side is concave, umbili- 

 cus is open; chambers are many, 

 not much increasing in size as 

 added. Diameter 0.30-0.55 

 mm. a. Spiral view; b, umbilical 

 view; c, edge view Trochammina rolaliformis 



X100 



49 (47) Final chamber is extended as a bulging lobe covering the umbilical area; whorls are few; chambers increase 

 rapidly in size as added. Diameter 0.40-0.50 mm. a, Spiral view; b, umbilical view; c, edge 

 view Trochammina nana 



18 



