CHAPTER IT. 



OF THE FAMILY GROMIDA. 



76. The members of the Family Gromida accord with the imperforate Foraminifera in 

 the characters furnished by their sarcode-bodj% M'hich puts forth its pseudopodial extensions 

 only from a single aperture ; but differ from them in having that body enclosed only in a mem- 

 branous test, which may be reduced to such tenuity as to be scarcely distinguishable. By 

 M. D'Orbigny this family was altogether ignored, no member of it having been known when 

 he first applied himself to the systematic study of the Foraminifera, and no mention havuig 

 been made in his subsequent writings even of its typical genus Groinia discovered by 

 M. Dujardin in 1835 (xxxv), notwithstanding the clear demonstration given by that 

 admirable observer of its close relationship to Miliola (xxxvi). Not less completely was 

 this type excluded by Professor Ehrenberg from his systematic arrangement of Bryozoa 

 (xl) ; the genus Gromia being apparently regarded by him as allied to Arcella and D'lJJlugia, 

 which he ranked as Infusoria. It was by Professor Schultzc (xcvii) that Gromia and its 

 allies were first introduced into a complete systematic arrangement of the Foraminifera ; but 

 he placed so much higher a value on the unilocularity of the " test " than on any other 

 character, as to associate them with Arcella and BiJjJugia, whose animals are of the Amoeban 

 type, with Trinema and Eughiplia, whose animals are Actinophryan in character, with Squamidina, 

 which has an imperforate calcareous shell of the Milioliue type, and with Orulina, whose shell 

 is perforated and hyaline, in the Family LagynidcB of his Monothalamia Testacea, — an 

 association which must be altogether incorrect if there be any truth in the principles laid down 

 in the preceding Chapter, as being those on which alone can any approach to a natural 

 classification of Foraminifera be founded. Between the " test" of Gromia and that of Arcella, 

 indeed, there is but little difference ; but between the animals which form and inhabit these 

 " tests" respectively, the difference is as wide as any that is known to exist in the whole 

 Rhizopod series ; and this difference has been cleai'ly recognized by MM. Claparede and 

 Lachmann (xxv). 



Genus I. — Lieberkuhnia (Plate II). 



77. This genus is the one of the whole Order Beticularia in which the envelope of the 

 sarcode-body is reduced to its minimum ; so that it approaches most nearly to the absolutely 

 naked condition, and may in consequence be most advantageously studied as a type of the 

 group, holding the same position in the Rcticulose series that Amccba does in the Lobose, and 



