Nomenclature of the Poraminifera. 175 



to the width of the shell) from the periphery. The cell-growth 

 also often becomes wild, the later chambers irregular and heaped, 

 being outspread on the granulated surface of the upper side. 

 The rough and prickly surface is a very constant character in 

 this Calcarina, although some very minute forms show it only in 

 an umbilical boss and a prickle on the periphery of each chamber. 

 What seems to be a large aperture in these figures arises from 

 the fracture of the newest chamber, which is, until well coated with 

 exogenous matter, extremely thin. In well-preserved specimens 

 of the typical forms we find that the real aperture, which is 

 essentially a slit, as in the true RotalicB, becomes bridged over 

 by delicate bars of shell-matter. Calcarina is a subgenus of 

 Rotalia, characterized by its excessively spinous coating and 

 cribriform aperture. In its spines, in the copiousness of its 

 exogenous matter (which is tubuliferous), and in its generally 

 cribriform aperture, it afibrds us an analogy to the Polystomella 

 erispa ; whilst other Rotalia have on their part a corresponding 

 analogy to the smooth- shelled Nummulina and Amj)histegina. 

 Rotalia Beccarii, often prickly and even spinous, is the linking 

 form between Calcarina Spengleri and the ordinary Rotalia, and 

 at the same time is rich in varieties isomorphous with many 

 conditions of Pohjstomella. 



Rotalia [Calcarina) Spengleri is found in all warm seas. This 

 is the Siderolites calcitrapoides of Lamarck, and Siderolina lavi- 

 gata, D'Orb., both from Maestricht. The latter is Fichtel and 

 MolFs var. e. 



26. Nautilus repandus. Page 35, pi. 3. figs. a-d. " Recent : 

 zoophytic concretions, Mediterranean.^^ 



This is a true Rotalia, and is a typical form of a large num- 

 ber of varieties which have their cells numerous but very variable 

 in their convexity, — so much so that they often produce a much 

 more expanded shell than the one here figured, and even irre- 

 gular in growth ; on the other hand, they may become contracted 

 and few-celled, forming a thick conical shell. The aperture is 

 usually a large slit at the base of the last chamber ; but in some 

 of the more compact forms, in which the chamber-walls are 

 flush, the apci'ture passes into the condition of a notch : hence 

 the forms of aperture once supposed to be respectively charac- 

 teristic of Rosalina and Rotalia are in this species shown to be 

 non-essential. The specimen figured by Fichtel and Moll is 

 probably not very well drawn ; for in specimens of similar size 

 and form we find the spire better marked. 



A flatness of the septal face is a very usual feature in this 

 species. 



This is a world-wide species in its typical condition; and its 

 many varieties are equally abundant and common. In deep 



