PLATE CXVIII. 



Sabella Belgica, the auricoma of the Zoologia Danica. There are 

 now, including the species Pectinaria Guildingii, three species of the 

 tribe of Amphitrite that appear to be more analogous to each other 

 than either of the rest, and which may be perhaps considered as the 

 whole amount of the true species of this family at present known : 

 these are Pectinaria Belgica, Capensis, and the third species Guild- 

 %gii, which is now added to the number. Each of those possess 

 characters that are specifically distinct, and among others, they offer 

 one by which they may be distinguished even by the casual observer, 

 without descending to the less obvious characters, by which the 

 respective species are discriminated. The Pectinaria Belgica is of a 

 linear form, and the shelly or arenaceous habitation of sufficient di- 

 mensions only to accommodate the bod^, and this is therefore linear 

 also ; or in other words a subconical cy Under, having the interior part 

 of the shell rather larger, and tapering gradually to the posterior 

 extremity, Pectinaria Capensis is about twice the breadth of Belgica, 

 while the length is only the same. Our present species is rather more 

 considerable in point of size, and is, in proportion to its length, nearly 

 twice the breadth of Capensis, or at least thrice that of Belgica, 

 and has the sandy habitation broad and bulky in proportion. 



We believe our readers are well peisuaded that few authors 

 would more cautiously abstain from every kind of innovation upon the 

 estabhshed arrangements of preceding Naturalists than ourselves, or 

 any one be less inclined to adopt changes that should appear to our- 

 selves unnecessary, if not trivial, at the same time that we are ever 

 disposed to approve of such amendments as in the present state of 

 science may be deemed desirable. It is obvious to our view that the 

 genus Sabella, as proposed by Linnaeus, is not precisely what the accu- 



