Foraminifera from the Coast of Norway, 299 



Biloculina buUoides, D'Orb. Ann. Sc. N. vii. p. 21)7- no. 1. pi. 16. f. 1-4 ; 



Modeles, no. 90. 

 Pyrgo Icevis, Defr. Diet. Sc. Nat. pi. 88. f. 2. 

 Biloculina Icevis, D'Orb. Ann. Sc. N. vii. p. 298. no. 8. 

 Biloculina aculeata, D'Orb. Ann. Sc. N. vii. p. 298. no. 3 ; Modeles, no. 31. 

 Biloculina depressa, D'Orb. Ann. Sc. N. vii. p. 298. no. 7 ; Modeles, no. 91. 



Shell ovate, gibbous or compressed, white, opake, smooth or 

 sometimes delicately striate (fig. 32), sometimes roughened by 

 fine granulation; externally showing two loculi or chambers, 

 the larger (last) one overlapping the edges of the penultimate 

 chamber; the internal chambers formed on the same plan. 

 Chambers few (six to nine), disposed parallel to the long axis of the 

 shell, regularly alternating on one side and the other, cochleate, 

 of a more or less ovate outline and convex externally, resembling 

 the bowl of a spoon with the edges strongly incurved ; the edges 

 of each chamber fitting over the edge of the shell constructed 

 by earlier chambers. The chambers have no inner wall of their 

 own*. The aperture is a transverse terminal slit, modified and 

 encroached upon by a tongue-like lamina on its inner side. 



This shell varies from the striking globosity of the finely 

 striated variety (figs. 32 Sc 33) to the flatter and oval form (figs. 

 30 & 31) : a much greater degree of flatness obtains in specimens 

 collected from other sea-sands [B. depressa^W Ovh.) ; and, on the 

 contrary, a lateral compression gives rise to another extreme form 

 in B. contraria, D^Orb. Occasionally, from the varying amount 

 of overlapping of the outer chamber, either full or meagre at 

 the edges, the general outline is variable. In fig. 30 the shell 

 is subquadrate in outline, and almost three-lobed on one of its 

 surfaces, owing to the deficiency of one part (base) of the last 

 chamber, and the swollen condition of its two overlapping edges. 

 In fig. 31 we have a side-view of a form intermediate, by its 

 partially-swollen sides, between figs. 28, 29, & 30. [B. clypeata, 

 B. simplex, and B. inornata, D'Orb., are varieties amongst these 

 Norwegian Miliolce.) Fig. 32 diff'ers by its greater globosity 

 and by its striation from the other Biloculince here figured ; the 

 latter character is rare in Biloculina : judging, however, from the 

 uncertainty of ornamentation in other Foraminifera, especially 

 Quinqueloculina, this character of striation is scarcely available 

 for specific value. 



Biloculina is very common in the recent and the Tertiary sea- 

 sands, and has supplied numerous so-called " species'' to authors. 

 The forms, for instance, figured by D'Orbigny in his ' Foram. 

 Foss. Bass. Vienne,' pi. 15 & 16, may be advantageously studied 

 in this light. 



* The tongue-like plate in the aperture of the shell is appai-ently the 

 only representative (or homologue) of the inner wall of each segment. 



