93 MOLLUSC A. 



conical form, the older ones having been effaced in succes- 

 sion. The genus Tulaxodes of Guettard is not, perhaps, 

 entitled to be considered as distinct. 



The AMPLEXUS of Sowerby belongs to this division. It 

 is nearly cylindrical, divided into chambers by numerous 

 transverse septa, which embrace each other with their re- 

 flected margins. It contains one species from the limestone 

 rocks of Ireland, but we may add that it has been supposed 

 to belong to the zoophytes rather than the mollusca. 



3. Multilocular testacea of a globular form. The first 

 genus of this section is the MILIOLA. The shell is com- 

 posed of three or four oval cells, turning round an axis pa- 

 rallel to their longest diameter. Many recent species of 

 this genus are common on our shores ; they were included 

 by Montagu in his genus vermiculum. 



In the RENULINA the cells are narrow, linear, unilateral, 

 curved into a part of a circle, and all situate on the same 

 plane. The smallest cell forms a little arch round a mar- 

 ginal axis, and the others are placed contiguous to this on 

 the same side, The species are all fossil. 



The GYROGOXA was for many years viewed as a shell of 

 a spheroidal form, composed of linear, curved, grooved, 

 pieces, terminating in two poles, the external surface obliquely 

 spiral, the spires terminating at each pole, and as found only 

 in a fossil state. But more recent observations have con- 

 nected it with the seed vessel of the genus chara. 



The shells of the genus NUMMULITES are remarkable for 

 their lenticular form. The external surface is smooth, and 

 the cells concealed, but internally the transverse shells are 

 disposed in a spiral discoid form. The cells are imperfor- 

 ate ; they are the camerinae of Bruguiere, the helecites of 

 Guettard, and the discolithes of Fortis. This last author 



