. dredged wp from the Gulf of Manaar. 363 



Specimens from the Gulf of Manaar and Basse Bocks. 



FORAMINIFEEA. 



Gypsina melohesioides. 



I observe that many of tlie " Melobesian nodules" in the 

 Gulf of Manaar are chiefly made up of layers of Melohesice 

 intercalated with Gypsina melohesioides ^ Holocladina pustuli- 

 fera, and Carpenteria utricularis ; so that, as before stated, the 

 Foraminifera are as much enf^as-ed in formino- them as the 

 Calcareous Algte. How far they may be built upon by various 

 kinds of sponges and other organisms afterwards (that is, as 

 they are progressively enlarged by such lamination) must de- 

 pend a great deal on accidental circumstances ; but there can 

 be no doubt that, if ever fossilized, they will each contain a 

 great variety of organic remains. Hence we should not be 

 surprised at finding nodules in the Chalk similarly constituted 

 in this respect. 



Rotalia arenacea, n. sp. (PI. XVIII. fig. 10.) 



Test translucent, parasitic, sessile, subcircular, subtrochoid, 

 flat towards the margin. Trochoid portion formed of a spire 

 of nautiloid chambers (fig. 10, a), contrasting strongly in its 

 brown colour, as seen through the test, with the flat part 

 (fig. 10, 6), which appears to be without chambers and colour- 

 less. Composed througliout of a heterogeneous mixture of 

 minute angular grains of quartz mixed with the remains of 

 microscopic organisms. Size of largest specimen about 

 l-45th inch in diameter, of which the central half is occupied 

 by the coloured or nautiloid part mentioned. 



Hah. Marine, on hard objects ; in company with Rotalia 

 spiculotesta. 



Log. Gulf of Manaar and Basse Rocks. 



Ohs. This is almost a facsimile of R. spiculotesta, with 

 which it is associated ; and but that the test of the latter is 

 formed of calcareous spiculiform bodies produced by the animal 

 itself, while that of the former is composed of foreign material 

 (grains of quartz &c.), with which the peculiar spiculiform 

 bodies of the latter, too, are often mixed, I think there would be 

 hardly any appreciable diff'erence. It is much more abundant 

 than R. spiculotesta, whose shell is somewhat larger, whiter 

 towards the margin or in the uncoloured portion, and darker 

 in the centre. The flattened rim, although extremely thin, 

 still may be chambered. 



It is remarkable that R. concamerata (Williamson, Recent 



