MOLLUSCA. 431 



ceding genera, constitutes all their claim to be included in 

 the present order *. 



Order II. SEPIACEA. 



Destitute of a multilocular shell. 



The sac is strengthened by horny or testaceous plates, 

 unless where the habits of the animal render such support 

 unnecessary. 



* Since the days of LINNJEUS, our knowledge of the Multilocular testacea 

 has been greatly enlarged. He contented himself with arranging all the 

 species with which he was acquainted under one genus, but, in consequence 

 of modern industry, even the genera exceed the number of Linnaean species. 

 Many recent species have been discovered, by the aid of the microscope, 

 among the sand on the sea-shore, and a still greater number in a fossil state 

 among the calcareous strata. These newly discovered kinds exhibit many 

 different characters, and have compelled Conchologists to institute so many 

 new genera for their reception, that the genus Nautilus of LINN.KUS appears 

 rather as the head of a family or order, than as a separate genus of univalve 

 shells. In this department the names of BRU&UIERE, LAMARK, MONFFORT, 

 PARKINSON, and SOWERBY, deserve respectful notice ; and it is from their 

 writings that the following remarks concerning the multilocular testacea have 

 been extracted. The multilocular testacea may be divided into three sec- 

 tions : the first including those which are obviously spiral j the second, those 

 which are produced ; and the third, those which are of a globular or lenticu- 

 lar form. These sections are merely provisional, and are only intended to 

 render more obvious and intelligible our notices of the genera. 



1. The spiral multilocular testacea. At the head of this first division 

 stands the modern genus NAUTILUS, in which the turns of the spire are con- 

 tiguous, and the last whorl incloses the others. The partitions are perfo- 

 rated by a tube. We possess on our shores several species of this genus, of 

 which the N. crispus is the most common. 



In form, the genus LENTICULINA is nearly related to the former. The 

 margin of the mouth reaches to the centre of the shell on both sides, and the 

 partitions are destitute of a syphon. LAMARK is in possession of a recent 

 shell of this species from the sea near Teneriffe. 



The shells which Mr SOWERBY, in his Mineral Conchology, has figured 

 under the genus ELLIPSOLITHES, have the whorls conspicuous, although the 

 mouth clasps the body whorl. But it is easily distinguished from the other 

 genera with which it is related by its elliptical form. 



