ABBEEYIATIONS. 49 



With respect to genera, those who believe in their real exist- 

 ence as " ideas of the creating mind," will be disposed to set 

 aside many random appellations given to particular shells 

 without any clear enunciation of their characters ; and to adopt 

 later names, if bestowed with an accurate perception of the 

 grounds which er title them to generic distinction.* 



Authority for specific names. The multiplication of synonyms 

 having made it desirable to place the authority after each name, 

 another source of evil has arisen; for several naturalists (fancy- 

 ing that the genus maker, and not the species maker, should 

 enjoy this privilege) have altered or divided almost every genus, 

 and placed their signatures as authorities for names given half 

 a century or a century before by Linnaeus or Bruguiere. The 

 majority of naturalists have disowned this practice, and agreed 

 to distinguish by the addition of " sp." the authorities for 

 those specific names whose generic appellations have been 

 altered. The type of a genus should be the species which best 

 exhibits the characters of the group, but it is not always easy 

 to follow out this rule ; and consequently the first on the list is 

 often put forward as the type. 



ABBREVIATIOK-S. 



Etym. , etymology ; Syn. , synomym ; Distr. , distribution ; 



MS., impublished ; Sp., species ; B.M., in the British Museum. 



Distr. , Norway — New Zealand ; including all intermediate 



Foss., Lias-chalk: implies that the genus existed in these 

 and all intermediate strata. Chalk — ; means that the genus has 

 existed from the chalk up to the present time. 



Depth — 50 fms. implies that the genus is found at all depths 

 between low- water mark and 50 fathoms. A fathom = 6 feet. 

 \, one-fourth real size ; f , magnified four times. 



Lat., breadth; Long., length; Alt., height or thickness. 

 Unc, an inch; Lin., a line or -jV o^ an inch; Mill., a milli- 

 metre or 2V of an inch. 



* Several bad practices — against which there is, unhappily, no law — should be 

 strongly discountenanced. First, the employment of names already in famDiar use 

 for other objects ; such as cidaris (the title of a well-known genus of sea-urchins) for 

 a group of spiral shells; and arenaria (a property of the botanists) for a bivalve. 

 Secondly, the conversion of specific into generic titles, a process which has caused 

 endless confusion ; it has arisen out of the vain desii-e of giving new desigtations to 

 old and faouliar objects, and thus obtaining a questionable sort of fame. 



