MANUAL OF ZOOLOGY. 



unknown cement. Its walls may or may not be traversed by 

 pseudopodial foramina. 



Fig. 4. Morphology of Foraminifera. a Lagena vulgaris, a monothalamous Forami- 

 nifer; b Miliola (after Schultze), showing the pseudop 

 oral aperture of the shell ; c Discorbina (after Schultze), showing the nautiloid 



ring the pseudopodia protruded from the 



shell with the foramina in the shell-wall giving exit to pseudopodia ; d Section of 

 Nodosaria (after Carpenter) ; e Nodosaria hispida / f Globigerina bulloides. 



As regards the form of the shell, the Foraminifera may be 

 conveniently, though arbitrarily, divided into two sections : 

 the Monothalamia and the Polythalamia. In the first of these 

 sections (fig. 4, a), comprising the so-called " simple " or " uni- 

 locular " Foraminifera, the shell consists of a single chamber, 

 and the animal is, in fact, nothing more than a little mass of 

 sarcode enveloped in a calcareous covering. Lagena, with its 

 beautiful flask-shaped shell, may be taken as the type of this 

 division. Another well-known unilocular form is Entosolenia, 

 which is like Lagena in shape, but has the tubular neck reversed, 

 so as to be inserted into the interior of the test. In the 

 Polythalamia, or " multilocular " Foraminifera, the shell ' is 

 composed of many chambers separated from one another by 

 divisional walls or " septa " (fig. 4, c, d, e) each of which is per- 

 forated by one or more openings, " septal apertures," by means 

 of which the sarcode occupying the different chambers is 

 united into a continuous and organic whole, the connecting 

 bands being called "stolons." Complex as their structure 

 often is, the compound Foraminifera are, nevertheless, formed 

 by a process of continuous gemmation or budding from a 



