84 FAMILY MILIOLIDA. 



of the proper Milioline type of structure ; that subdivision of the chambers^ which we find to 

 characterise the liighest types of each series of Foraminifera {% 64), being here superinduced 

 upon tlie simple MilioUnc type of growth. In the existence of that subdivision we have a 

 relationship of analogy or parallelism to Orbiculina, Orbitolitcs, and Aheolina ; but in plan 

 of growth Fabularia is so distinctly related to Miliola, that its genetical derivation is 

 to be looked for rather in the varietal modifications of the last-named type, than in transi- 

 tional forms connecting it with those just named, which will be found to have (so to speak) 

 a distinct line of descent. 



120. Geological Distribtdion. — The genus Fabidaria is at present only known in a fossil 

 state, and it has not been met with elsewhere than in the tertiaries of the Paris basin, being 

 especially abundant at Grignon. 



Genus IX. — Peneroplis (Plate VII). 



121. Hisfon/. — The germs Peneroplis was first instituted by Montfort (lxvii) to distinguish 

 a peculiar type of minute polythalaraous shells, which had been previously described and 

 figured by Schroter (xcvi) and by Fichtel and Moll (xlv), the latter of whom had ranged it 

 with numerous others under the comprehensi\'e designation JVauHlus. By Montfort its 

 distinctive character was correctly indicated as " bouche de toute la longueur de la base, et 

 percee serialement par une file des pores ;" but he seems to have very erroneously inter- 

 preted the signification of those pores, imagining that the principal chambers are subdivided 

 into cells, each occupied by a distinct animal, of which cells the pores are the separate orifices. 

 Lamarck* (lix), not adopting Montfort's genus, referred the Naufilns planafus oi Fichtel and 

 Moll to the genus Gristellaria, with which it has no relationship whatever ; but the genus 

 FeneropJis was recognised by Blainville (vi) and by Ehrenberg (xxxix) ; and D'Orbigny has 

 applied this name, in his various writings on Foraminifera, to the form described by Fichtel 

 and Moll, whilst he has created one new generic term, Dendritina, for a series of varietal 

 forms in which there is a single large arborescent aperture instead of a single or multiple row 

 of separate pores, and another, Spirolina, for a varietal series in which the spire is prolonged 

 rectilineally into a row of cylindrical or subcylindrical chambers with an aperture resembling 

 that of BeridrUbia, this last being the Coscinospira of Ehrenberg. 



122. External Characters. — The ordinary form of the shell of Peneroplis (of which an 

 ideal representation given in Plate VII, fig. 18, is an extremely flat spire, of about two 

 turns and a half, opening out i-apidly in its last half turn. In the young shell each whorl 

 usually does little more than adhere to the margin of the preceding, so that the first-formed 

 portion is but slightly concealed by the subsequent growth ; but sometimes the earliest whorl 



* The Renidites of Lamarck and the Remdina of Blainville, which are quoted by Prof. 

 Williamson (ox, p. 44) as synonyms of Peneroplis, are (as already shown, % 98) aberrant forms of 

 Verteh-alina. 



