376 MESSES. E. HEEON-ALLEJSr AND A. EAELAND ON THE 



NOUBIA POLTMOEPHINOIDES, sp. n. (PI. XXXVII. figs. 1-15.) 



Test free, bilaterally compressed, consisting of two to four or more chambers 

 arranged in a compressed fusiform spiral. External surface moderately smooth, the 

 constituent particles being arranged with their flatter surfaces to the exterior. 

 Interior surface very rough, owing to the intra-projection of the more angular surfaces 

 of the constituent grains (figs. 3 & 5). Septal lines very obscure, sometimes indicated 

 externally by slight depressions (figs. 6, 7, 10). The walls of the chambers composed 

 of adventitious particles — sand-grains, shell-fragments, gem-particles, and sponge- 

 spicules— neatly cemented together. The test is less rigid than is usually the case in 

 the Lituolidse, and, when moistened, becomes soft and easily ruptured. Internal septa 

 of irregular construction, and more or less incomplete. In specimens laid open, the 

 septa are often seen to be formed by the building-in of large flattened particles (flakes 

 of mineral, or particles of molluscan shells) which, projecting into the internal cavity, 

 separate it into definite spaces (fig. 5). The chambers thu.s formed are often indicated 

 externally by a slight inflation of the shell, a feature especially noticeable as regards 

 the initial chamber, which may be prominent, as in some of the Polymorphinse. The 

 aperture is a terminal and irregular orifice closed by finer sand-grains, of which the 

 terminal portion of the test is sometimes entirely constructed (figs. 2, 4, 6, 7, 10, 12). 



Specimens of Nouria j)olymorphinoides often present a very striking appearance, 

 owing to a tendency of the organism to incorporate in its shell relatively large mineral 

 fragments (figs. 6, 7, 10), The "selective" tendency, however, cannot be described as 

 being exceptionally marked in this species, either in the Kerimba or in the New 

 Zealand specimens, the mineral fragments and shell-particles being normal constituents 

 of its environment, but we have examples of a closely related form from several widely 

 separated localities which exhibit the " selective " tendency in the most remarkable 

 degree, the test being entirely composed of acerate sponge-spicules, regularly cemented 

 together in parallel rows. We propose to take the present opportunity of describing 

 these specimens, although they have not been found at Kerimba. 



Nouria polymorphinoides varies in the relative proportions of the test, according to 

 the varying degrees of isomorphism with Polymorphina. The Kerimba specimens 

 range, on an average, between 1 and 1-9 mm. in length, and '6 to 1 mm, in breadth. 

 The thickness is usually rather less than the breadth. The New Zealand type is of 

 somewhat different proportions, the length varying between -70 and "S-S mm. and the 

 breadth between -25 and '30 mm. The thickness of the shell is rarely more than 

 half the breadth. The discrepancies are to some extent due to the neater con- 

 struction and less massive material employed by the New Zealand type, 



Nouria harrisii, sp. n. (PI, XXXVII. figs. 16-20.) 



Test free, fusiform, cylindrical to subcylindrical in section, consisting of two to four 

 chambers arranged in a polymorphine manner and constructed entirely of sponge- 



