14 
Transactions of the Society. 
the Upper Hils formation near Brunswick, and was since found in the 
French Gault at Montcley (Berthelin). 
At Folkestone M. Parker i was found in zone v., frequent. 
Vaginulina d’Orbigny [1826]. 
Vaginulina truncata Reuss (abnormal forms), plate II. figs. 9, 10. 
The fusion of two equally well grown individuals of the above 
•species is shown in fig. 9. It appears as if a growing hud of a similar 
form to the initial one had become attached to the oral end of a 
perfect specimen, at the stoloniferous line or apertural border. 
In fig. 10 we have a further corroboration of this interpretation 
in which a fully grown individual bears, upon the stolon border at 
the penultimate and last chambers, an embryonic Vaginulina. 
Both specimens were found at Folkestone in zone x. 
Vaginulina truncata Reuss var. robusta Berthelin and Chapman 
(a bigeneric outgrowth), plate II. fig. 13. 
This remarkable example is truly dimorphic (in the old sense of 
Ike term) ; * that is to say, it exhibits two distinct generic types 
Reginning as Vaginulina and succeeded by Frondicularia. 
The vaginuline commencement, after forming four chambers 
beyond the primordial, takes on the plan of growth of a Frondicularia 
of the F. archiaciana type, but slightly broader, and altogether in 
keeping with the coarse texture of the earlier part, 
This specimen was found in zone vii. at Folkestone. 
Vaginulina recta Reuss (abnormal forms), plate II. figs. 11 
and 12 a , b. 
The first of the specimens, fig. 11, is singularly interesting on 
account of the fusion of two individuals of different forms, namely B 
and A (of Schlumberger) ; or of the microspheric and megalospheric 
types respectively. The first half of the specimen is a somewhat 
twisted Vaginulina recta with a microspheric commencement and 
numerous and narrow chambers ; the later half is a perfect megalo- 
spkeric form of V. recta, and springs out of the seventh chamber of 
the parent test. The primordial sphere of the second half is partially 
enclosed in the last chamber of the first form ; and this would lead one 
to suppose that here we have an actual generation of a megalosphere 
which, failing to break free, continued to grow on in this dual fashion. 
Figs. 12 a, b represent a perfect individual of V. recta , to which is 
attached, at the apical end, another of the same species slightly broken 
* In consequence of the confusion which may he likely to arise from the different 
uses of the same term, that is, to mean either a combination of quasi-genera (Jones 
and Parker), or a dual form of the same species (according to Munier Clialmas 
and Schlumberger), it is here suggested that the earlier term of dimorphism be 
.substituted by bigenerism, with hi generic in an adjectival sense. 
