226 UPPER CRETACEOUS-LOWER TERTIARY FORAMINIFERA 



bordered above by a narrow delicate lip ; wall calcareous, distinctly perforate ; 

 surface very finely pitted. 



Dimensions of described specimen. 

 Maximum diameter = 0-41 mm. 

 Minimum diameter = 0-22 mm. 



Thickness = 0-26 mm. 



Main variation. 



1. Chambers 12-15, arranged in 2^-3 whorls. 



2. Coiling predominantly dextral (of 240 specimens picked at random, 62 



coiled sinistrally). 



3. Chambers in the last whorl 4^-5, rarely 5^. 



4. The surface is usually finely pitted, but in some specimens the pits become 



coarser. 



Remarks. Bolli (19576) removed this species from Globigerina to Globorotalia 

 because of the extraumbilical-umbilical position of the aperture. This was substan- 

 tiated by Loeblich & Tappan (1957a), Olsson (i960), Bolli & Cita (1960&), Reyment 

 (i960), Berggren (1962) and Hillebrandt (1962). The subgeneric classification 

 adopted by the last two authors is not followed here for reasons already explained. 



G. pseudobulloid.es (Plummer) is distinguished by its low, trochospirally coiled, 

 " globigerine " test ; its slightly raised initial spire ; its 4^—5 chambers in the last 

 whorl which are strongly inflated and increase very rapidly in size ; its large, strongly 

 inflated last chamber ; strongly incised sutures and finely reticulate surface. 



Subbotina (1953) confused G. pseudobulloides with Globorotalia compressa (Plum- 

 mer) and considered the former as a variety of the latter. However, both her 

 Globigerina compressa var. compressa Plummer and Globigerina compressa var. 

 pseudobulloides Plummer are mostly G. pseudobulloides (Plummer). Contrary to 

 Subbotina's observations G. pseudobulloides and G. compressa are two distinct species. 

 Subbotina also described as Globigerina varianta n.sp., forms which probably belong 

 to G. pseudobulloides (Plummer), Globorotalia quadrata (White) and Globorotalia 

 esnaensis (Le Roy). 



Hofker (1960^, i) studied the orthogenetic changes in the development of G. 

 pseudobulloides in the type Danian, the Paleocene rocks of Denmark, and the upper- 

 most white chalk of Holland and Belgium. Although he confused the present 

 species with apparently similar Hedbergella species in the Maestrichtian rocks below 

 and considered it to belong to the genus Globigerina it is of interest to review his 

 observations. 



Hofker (1960^ ; 78) stated that " this species, beginning in the uppermost 



white chalk (Skrivekridt) with knobs between the fine pores, gradually changes its 

 wall structure through the Danian from a pitted one towards a strongly honeycombed 

 one in the Paleocene clays above the greensand, indicating that those clays are of the 

 same age as the Midway Paleocene " However, as the Lower and Middle Danian are 

 missing in the sections studied, it was not possible to judge the suggestions of 

 Hofker (1960^, i) which were partially substantiated by Berggren (1962), that 



