344 ON THE ORDERS 



scribed, with the sexes distinct, and a body visibly articu- 

 lated on the outside so as to be composed, as it were, of a 

 number of annular segments. Now, as the Scarah&us 

 Sacer is evidently such an animal, it becomes necessary, 

 in order to attain the object proposed in the title of this 

 Essay, to investigate the composition of the division oiAn- 

 nulosa. In attempting this, 1 shall commence with the 

 Crustacea, not only as being the group which is according 

 to all appearance the nearest to the Cirripeda, but because 

 it is that of which I know so little, that 1 shall be glad to 

 dismiss it in as few words as it is possible to use, consist- 

 ently with my desire of proving that there is more unity 

 in the plan of Nature than has hitherto been suspected. 



Crustacea. 



They who may wish to be acquainted with these sin- 

 gularly constructed rather than beautiful animals, must re- 

 sort to the works of M. Latreille and Dr. Leach, the latter 

 having analytically done as much service to this branch 

 of Natural History as the other has synthetically. My 

 present object will be sufficiently gained by stating briefly 

 that some Branchiopoda, such as the genus Zoe, have ap- 

 peared both to Bosc and to Latreille to lead us to the Deca^ 

 poda, or those Crustacea which have the head confounded 

 with the trunk. The Stomalopoda of Latreille are not allowed 

 by Dr. Leach to be a distinct order, but merely the means 

 of transition from the Decapoda to the Amphipoda. They 

 are probably an osculant order connecting these : yet,if cer^ 

 tain analogical considerations be rigorously attended to, 

 they will find a place rather with the latter than with the 

 former. This besides is a distribution which seems suffi-^ 

 ciently authorized by tlie circumstance, that in. both the 



