GENUS SQUAMULINA. 67 



verts it into an OrbiciiUna ; and this, in the later stage of its existence, usually takes on the 

 cyclical mode of growth, whereby it is linked on to OrbitoKtes which ordinarily follows that 

 plan from the commencement ; whilst, on the other hand, the mere lengthening of its axis of 

 growth carries us from the discoidal Orhiculina to the fusiform Aheolina. The most peculiar 

 types at present kn6wn to belong to this series are Badylopora and Acicularia, which seem 

 to be formed upon somewhat the same plan as OrbitolUes, though separated from it by a 

 wider interval than exists elsewhere. — Hence we seem fully justified in bringing together 

 all these forms into a single Family, and in giving to this family a designation derived 

 from that one of its genera which seems most wideJij diffused both in space and in time, there 

 being none which can be regarded as typical in regard to form. The following tabular 

 arrangement of this family may assist in the appreciation of the relationships of its members. 



FAMILY MILIOLIDA. 



Squamulina. 



I I 



Nubecularia — Cornuspira. 



I I 



Vertebralina . . Miliola. 



I I 



Peneroplis . . . Hauerina. 



I I 



Orbiculina . . . .Fabularia. 



I I 



Alveolina Orbitolites. 



I 

 Dactylopora. 



I 

 Acicularia. 



Genus 1. — Squamulina (Plate I, fig. 22). 



81. The genus Squmitdina was instituted by Prof. Schultze (xcvii, p. 56) for a minute 

 monothalamion of which he found several specimens at Ancona, adhering to the surface 

 of Algae and to the side of a glass vessel in which sea-water had been long kept. The shell, 

 whose largest diameter is about l-.300lh of an inch, has the form of an irregular plano-convex 

 lens, being usually flat, or nearly so, on its attached side (which accommodates itself to the 

 surface whereon it grows), and convex on its free side, on some part of which — usually about 

 half way between the centre and the periphery — is a wide orifice from which the pseudopodia 

 issue. The shell is calcareous and opaque, and is destitute of pores ; its adherent layer is very 

 thin, and is with difiiculty detached from the surface to which it is attached. The substance 

 of the animal is of a brownish-yellow colour, as in Gromia ; its pseudopodia, however, seem 

 fewer and less disposed to subdivide and inosculate. 



