ABBREVIATIONS. 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 entitle them to generic distinction.” 
Authority for specific names. The multiplication of synonyms 
haying made it desirable to place the authority after each name, 
another source of eyil 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 Linneeus or Bruguiere. The 
majority of naturalists have disowned this practice, and agreed 
to distinguish by the addition of ‘‘sp.” the authorities fcr 
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. 
ABBREVIATIONS. 
Etym., etymology; Syn., synomym; Distr., distribution ; 
MS., unpublished ; Sp., species; B. I/., in the British Museum. 
Disir., Norway—New Zealand; including all intermediate 
geas. 
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 fins. implies that the genus is found at all depths 
between low-water mark and 50 fathoms. <A fathom = 6 feet. 
t, one-fourth real size; #, magnified four times. 
Lat., breadth; Long., length; Alé., height or thickness. 
Une., an inch; Lin., a line or y of an inch; Mill., a milli- 
metre or 35 of an inch. 
* Several bad practices—against which there is, unhappily, no law--should be 
strongly discountenanced. First, the employment of names already in familiar use 
ror other objects ; such as cidaris (the title of a well-known genus of sea-urchins) for 
& 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 desire of giving new desigtations to 
old and familiar obiects, and thus obtaining a questionable sort of fame. 
