GENUS ORBITOIJTES: — HISTORY. 
191 
simples ou multiples ; point de spirale.” Under this order are ranged the genera 
CycloUna (D’Orb, 1839), OrhitoUtes (Lamarck, 1801, and Marginopora, Quov et 
Gaimard, 1836), Orhitolina (D’Orb. 1847), and Orhitoides (D’Orb. 1847). As I shall 
have occasion to show that the first three of these genera cannot be separated from 
each other by any valid distinctions, and that the greater number of the species 
ranked under them by M. d’Orbigny (see his ‘Prodrome de Paleontologie Strati- 
graphique’) really belong to the same specific type, I must here cite the generic cha- 
racters which he assigns to them : — “ CycloUna, Coquille discoidale, chaque loge 
percoe de nombreux pores, faisant im circle entier aiitour des autres. L’esp^ce con- 
nue est de I’etage cenomanien. — OrhitoUtes, Coquille discoidale, plane, egale, et 
encroutee des deux cotes, pourvue de lignes concentriqiies. Loges nombreuses, 
par lignes irregulieres, transverses, visibles seulement au pourtour. Nous connais- 
sons deux esp^ces ; les premieres, de I’etage suessonien ; le maximum, dans les 
mers actuelles. — Orhitolina, Ce sont des Orbitolites a cotes inegaux ; Fun, convexe, 
eucroute, a lignes concentriques ; I’autre, concave, non encroute, rnontrant des loges 
nombreuses, par lignes obliques sur le cote, au pourtour. Nous connaissons de ce 
genre perdu six esp^ces ; les premieres, de I’etage albien ; les derni^res, de I’etage 
senonien.” 
6. The first approach towards a more accurate knowledge of the real nature of the 
Orbitolite, through an examination of its internal structure, was made (I believe) by 
myself, in my Memoir “ On the Microscopic Structure of NummuUna, OrhitoUtes, 
and Orhitoides,'' read before the Geological Society of London in November 1849, 
and published in its Quarterly Journal for February 18.50. The place assigned to 
this genus in the system of M. d’Orbigny not having been at that time made public, 
and all other zoologists and paleontologists having ranked it in close approximation 
to Lunulites and other Polyparies of the Bryozoic (Polyzoic) kind, I entered upon 
the examination without the least suspicion that this organism was to be regarded in 
any other light ; and that I was not undeceived in the course of it, may be attributed 
to the small number of specimens then placed at my disposal for the inquiry by my 
late friend Professor E. Forbes, and to the circumstance that these specimens were 
of the type that presents most resemblance to that of a Bryozoic polypary, and were 
all deficient in the central nucleus, which is the portion most indicative of their 
Foraminiferous nature. Nevertheless, the marked dissimilarity in structure which I 
found to exist between the disk of Orbitolite and the polypary of Lunulite or of any 
other undoubted members of the Bryozoic group, made me even then express myself 
doubtfully as to its title to be associated with them. In this Memoir, published two 
years previously to M. d’Orbigny’s first announcement of the fact, I showed that the 
genn?, Marginopora must be abolished, since its sole representative is so closely allied 
in structure to the Orhitolite of the Paris basin, that no doubt of their generic iden- 
tity can be entertained ; the existing M. vertehralis, in fact, being only specifically 
distinguishable from the fossil O. complanata, by a difference in the form of its super- 
2 c 2 
