NOMENCLATURE. 61 



name, another source of evil has arisen ; for several naturalists 

 (fancying 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 the authorities for names given 

 half a century or a century before, by Linnaeus or Beuguiere.* 

 British 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 changed. 



Types. The type of each genus sJiould he that species in 

 which the characters of its group are best exhibited, and most 

 evenly balanced. {Waterhouse.) It has, however, been cus- 

 tomary to take as the type, that species which the genus-maker 

 placed first on his list ; although by so doing there is risk of 

 adopting an aberrant form, or one which very feebly represents 

 the group, of which it is an obscure member. 



* The authorities appended to specific names, are supposed to indicate an 

 amount of work done in the determination and description of the species ; 

 when, therefore, the real author's name is suppressed, and a spurious one 

 substituted, the case looks very like an attempt to obtain credit under false 

 pretences. 



ABBREVIATIONS. 



EUjm., etymology. Syn., synonym. Distr., distribution. 



M.S., manuscript, i. e., unpublished. 



Sp., species. Brit. M., (in the) British Museum. 



Distr., Norway — New Zealand ; including all intermediate seas. 



Fossil, lias— chalk ; implies that the genus existed in these, and aU inter- 

 vening strata. Chalk — ; means that the genus commenced in the 

 chalk, and has existed ever since. 



Depth ; — 50 fms. ; genus found at all depths between low-water and 50 

 fathoms. A fathom is six feet. 



\ one-fom-th the real size ; \ magnified four times. 

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

 TJnc, (uncia) an inch. Lin., (linea) a line, the -^ of an inch. 

 Mill., millimetre, the twenty-fifth part of an inch. 



