60 HENRY B. BRADY. 



contour and in septation. In colour and shell-texture they 

 are precisely similar to Trochammina coronata. 



Trochammina lituiformis has been met with in the North 

 Atlantic (West Indies, 390 fathoms, and off the Azores, 900 

 fathoms), and at two stations in the South Atlantic, on the 

 coast of South America in about the latitude of Pernambuco 

 (350 and 675 fathoms). 



HORMOSINA GLOBULIFERA, n. Sp. PI. IV, figS'. 4, 5. 



Characters. — Test composed of a single spherical chamber 

 with a tubular neck, or of several (2 to 6) such chambers, 

 each larger than its predecessor and more or less embracing 

 it. Segments arranged in a straight or curved linear series, 

 terminating in a thin tubular neck. Texture very finely 

 arenaceous, surface smooth. Length of polythalamous 

 specimens often \ inch (3 millim.). 



The figures, 4 and 5 of PI. IV, afford a very insufficient 

 representation of this species, inasmuch as specimens are not 

 unfrequently found possessing four, five, or even more 

 chambers, and of correspondingly increased dimensions. In 

 default of room for sufficient figures, the object has been to 

 illustrate a tendency not uncommon amongst Foraminifera, 

 which shows itself strikingly in this particular species, 

 namely, the cessation of growth after the formation of a 

 chamber of relatively large size. As a rule the specimens of 

 Hormosina glohulifera which have the largest number of 

 segments are those with the smallest initial chambers, and, 

 on the other hand, if a very large primordial chamber is found 

 the test usually remains monothalamous and no further 

 growth takes place. A comparison of the size of the Lageni- 

 form test (fig. 4) with that of the earlier segment of fig. 5, 

 will illustrate this fact. The rule nolds good not only 

 of the first chamber, but in varying degree to the 

 life-history of Foraminifera generally. It is very com- 

 monly seen in polythalamous species that, with the forma- 

 tion of a chamber of abnormal size, the growth, that is, the 

 continued segmentation of sarcode, is abruptly stopped. 

 Instances of this occur in every section of the Order. What- 

 ever, therefore, may be the significance of monothalamous as 

 distinct from polythalamous tests amongst the Rhizopoda of 

 other groups, the character in this case is not of specific, still 

 less of generic importance. 



There is no difficulty in distinguishing these Hormosince 

 from their Lituoline isomorphs by their regularity and 



