REPOET ON THE FORAMINIFERA. 
375 
a slightly raised border. The diameter of the larger specimens is about ^tli inch 
(OT mm.). 
Apart from the peculiarity of its structure, Pavonina fiabelliformis derives some 
interest from the fact that, after its discovery by d’Orbigny in 1826 or earlier, the 
species was lost sight of for more than fifty years, and during that time, in the absence 
of specimens, various conjectures were made as to the affinities of the type, all of which 
have proved to be far wide of the mark. The specimens originally described were found 
by d’Orbigny in shore-sand from Madagascar, and it has been with great pleasure that 
I have recently met with the species in similar material collected by my friend Mr. L. 
Kitching near Tamatave, on the east coast of that island. 
I have notes of the occurrence of Pavonina fiabelliformis from nine or ten localities, 
namely : — off Culebra Island, West Indies, 390 fathoms ; Madagascar, shore-sand ; 
Seyehelle Islands, shallow water ; Port Louis, Mauritius, harbour mud ; off Calpentyn, 
Ceylon, 2 fathoms; off Raine Island, Torres Strait, 155 fathoms; Nares Harbour, 
Admiralty Islands, 17 fathoms; and Honolulu Reefs, 40 fathoms. Moebius’ specimens 
were from the Mauritius, and in Mr. F. W. Millett’s collection there are examples from 
the coast of the Korea. 
Spiroplecta, Ehrenberg. 
Ileterohelix, Ehrenberg [1843], 
Spiroplecta, Ehrenberg [1844], Parker and Jones, Brady, Balkwill and Wright. 
Textularia (pars), Parker and Jones [1865], Brady, Norman. 
The term Ileterohelix was originally assigned by Ehrenberg to this group of 
Textularince, but was almost immediately changed by him, for no very obvious reason, to 
Spiroplecta. The latter name is now in very general use, and there seems no advantage 
in reverting to the earlier one on the mere ground of priority, as the same author is 
concerned with both. 
The test of Spiroplecta is normally dimorphous ; the chambers are planospiral at the 
commencement and are subsequently arranged, as in Textularia, in two alternating series. 
In rare instances it exhibits a tendency to become trimorphous, by the further addition of 
a line of uniserial chambers with a central terminal aperture. 
The test presents the same degree of variation in point of texture as that of the typical 
Textularice ; it is thin and transparent in Spiroplecta rosulci, thicker and opaque in 
Spiroplecta annectens, and coarsely arenaceous in Spiroplecta biformis. 
The two species of Spiroplecta described by Ehrenberg in the Mikrogeologie, were 
based on specimens of Cretaceous age, and there does not appear to be any record of 
the occurrence of the genus between the Mesozoic and the Post-tertiary formations. In 
the living condition the type is widely distributed but by no means common. 
