,111 



in a shelly covering. If the former should prove to have been the 

 case, — if it should be found that the whole soft organism was able to 

 squeeze its numerous segments through the equally numerous, con- 

 stricted, oral passages, — it will be an additional evidence of the low 

 organization of the group, inasmuch as we can scarcely conceive of 

 anything in the shape of digestive canals and other concomitant 

 appendages being subjected to such a compression as this with 

 impunity. 



There appears at the same time to be little doubt that the small 

 calcareous papillae and other projections seen in the interior of each 

 cell, are additions which have been chiefly, if not wholly, made after 

 the formation of the calcareous cell itself. Some of them exhibit 

 traces of a laminated structure, and occasionally, as at 2, e, the pseu- 

 dopodian tubes can be seen prolonged into and even through them. 

 The greater number of the tubes, however, appear to be blocked up 

 by this internal accretion of line ; we especially observe this to be 

 the case in the septa, as seen in the horizontal section (fig. 1, g), 

 where the foramina, which originally penetrated the entire septum, 

 as is still the case with that in front of the anterior chamber, are 

 now seen to be arrested midway ; the anterior half of each septum 

 consisting of the secondary growths of calcareous matter, which they 

 do not usually penetrate. 



Fig. 3 reveals another new feature in the structure of the Foramini- 

 fera. It represents a small portion of the horizontal section of Amphis- 

 tegina Antillarum. This species is more depressed than A. gibbosa, 

 and also differs from it in the fact, that, in addition to the ordinary 

 arrangement of the septa common to the genus, each cell or chamber 

 in this species is subdivided into rhomboidal compartments by secon- 

 dary septa arranged at nearly right angles to the primary ones. These 

 subdivisions especially occur near the external or peripheral portion 

 of each segment, which is the part represented in fig 3 ; a is the 

 outer part of one of the primary septa ; b and b' respectively repre- 

 sent some of the secondary ones. The latter appear to be sometimes 

 complete, whilst at others they are but partial, having apparently an 

 opening in the centre where the diaphragm has not been perfectly 

 closed ; but on this latter point I am not quite certain. Each of 

 these septa exhibits the double structure which all recent observa- 

 tions indicate to be universal amongst the Foraminifera. Within 

 these areas are seen the beautifully foraminated structures which 

 constitute the lateral parietes of the shell. But the most curious 

 feature in this species is found at the periphery of the horizontal 



