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ME. W. K. PAEKEE AND PEOFESSOE T. E. JONES ON SOME 
and therefore, whilst we have some doubt as to the two-celled forms that have either no 
surface-ornament, or a sculpturing common to Nodosaria and Lagena , here we have 
satisfactory means of diagnosis. 
Everywhere in the Foraminiferal group, we have most curious instances of Isomor- 
phism , not merely between nearly related species, but between even the diverse forms of 
separate families (as between those of the Vitreous and Porcellanous Series). In the 
case under notice isomorphism may be said to occur between three closely cognate 
specific groups : thus, the specimen of Lagena before us has imitated a Nodosaria ; whilst 
those already spoken of as taking on a second chamber obliquely have the habit of a 
young Polymorphina (see fig. 46). 
Lagena Melo is not uncommon in company with other Lagence , though not so com- 
mon as the smooth, sulcate, honeycombed, and marginate varieties. For its occurrence 
(recent and fossil) in the Mediterranean Area, see Quart. Journ. Geol. Soc. vol. xvi. 
Table, p. 302. 
Lagena sulcata , Walker and Jacob, Var. (Entosolenia) squamosa, Montagu, sp. Plate 
XIII. figs. 40, 41 (Arctic) ; Plate XVI. figs. 11 a, 11 b (North Atlantic). 
This represents a state of ornamentation peculiar to the Lagence amongst the “ hyaline,” 
and to certain varieties of Miliola Seminulum among the “porcellanous ” Foraminifera. 
In L. Melo the cross-bars are often weaker than the longitudinal ribs, and pass straight 
across from rib to rib, like the secondary veins in a monocotyledonous leaf, such as 
Alisma, Myrsiphyllum, &c. In L. squamosa, however, not only have the secondary rib- 
lets become equal to the primary, but, by the zigzag inflection of the latter, a nearly 
regular hexagonally areolated ornament is produced, reminding one strongly of the 
polygonal meshes produced by the more perfect reticulation of the woody tubes in a 
dicotyledonous leaf. Early observers, using but imperfect microscopes, compared this 
retose ornament with a scaly skin of a fish (see Williamson, Monograph, p. 12). 
In fig. 34 we have noticed a variety of L. sulcata in which a few secondary bands had 
united with the main ribs, commencing, as it were, the honeycomb-pattern. 
Fig. 40, the largest of our specimens, is from the Hunde Islands* (Dr. P. C. Suther- 
land), 50 to 70 fathoms ; and the smaller one from the Arctic Ocean (MacAndrew and 
Barrett). 
L. squamosa is of world-wide occurrence ; but, like L. Melo, is not so abundant as the 
long flask-shaped and the marginated forms. Reuss has it from the Black Crag of 
Antwerp, and we have it fossil from Castel Arquato. By far the bulkiest specimens of 
L. squamosa that we have seen are from a Tertiary sand, which, rich in many varieties 
of Lagence , in Ovulites, Polymorphina, and Vertebralina, was taken from the inside of a 
Cerithium giganteum from Grignon (page 419, note). 
In this reticulate Lagena the neck is usually intussuscepted (Entosolenian) ; in the 
large fossil form ( L . tubifero-squamosa, Parker and Jones, Plate XVIII. fig. 7), however, 
* Professor Williamson has also noted its occurrence here (Monogr. p. 12). 
