REPORT ON THE FORAMINIFERA. 
137 
Nubecularia divciricata has only been observed in three localities : — Humboldt Bay, on 
the north coast of Papua, 37 fathoms ; off Raine Island, Torres Strait, 155 fathoms ; and 
off Tongatabu, Friendly Islands, 18 fathoms. 
Sub-family 2. Miliolininse. 
( Miliola and Miliolites, Lamarck.) 
Messrs. Parker and Jones, recognising the close relationship which exists amongst the 
subordinate groups of the more strictly Milioline Foraminifera, and the impossibility of 
dividing the series except by lines more or less lax and conventional, treat the whole as 
constituting a single genus, Miliola, and employ the d’Orbignian terms Biloculina, 
Spirolocidina, Triloculina, and Quinqueloculina in subgeneric sense. This method of 
dea lin g with the subject presents certain advantages, and so long as it does not entail 
a system of trinomial nomenclature it may be adopted without inconvenience. I 
venture only to differ from the authors in one minor point, namely, the questionable 
desirability of attempting to separate the Triloculine from the Quinqueloculine forms. 
The morphological relationship between the first two of these subgeneric groups, 
Biloculina and Spirolocidina, involves but little difficulty, and is readily understood. 
Typically the plan of growth is the same, — two chambers on the same plane to each con- 
volution ; but whilst Biloculina has wide, somewhat inflated segments, each of which in 
its turn encloses all those previously formed on the same side, so that only two segments 
are visible externally, Spirolocidina has narrow, non-embracing chambers, arranged 
alternately and symmetrically, so that every segment is seen on both sides of the shell. 
These are distinctions so generally accepted, and under ordinary circumstances so easily 
recognised, that the occurrence of an occasional specimen with intermediate characters is 
of no practical inconvenience. 
But with the Triloculine and Quinqueloculine members of the series the case is 
otherwise. The subdivision of the Miliola proposed by d’Orbigny in his Tableau 
nffithoclique de la classe cles Cephalopodes, 1 has been employed by systematists, with but 
few exceptions, to the present time. It contains the two following generic descriptions 
under the family Agathistegues : — 
“ Genre III. Triloculina. — Loges opposees sur trois cotes ; la meme forme a tous les 
&ges ; trois loges apparentes.” 
“ Genre Y. Quinqueloculina. — Loges opposees sur cinq cotes ; cinq loges apparantes.” 
The whole weight of the distinction embodied in these definitions hangs on the words 
“ a tous les ages,” which, it is scarcely necessary to point out, admits a most undesirable 
basis for the division of an unusually variable group. The number of varietal forms that 
can be said to have uniformly only three external segments is exceedingly limited, whilst, 
1 Annales des Sci. Nat., 1826, vol. vii. pp. 299, 301. 
