2o8 Mr. Cosmo Melvill on the 



of specific immutability, is, in these enlightened days, 

 vigorously assailed, but, as just pointed out, there are certain 

 forms of this genus apparently unapproached and with no 

 close relationships i7iter se. The case is widely different 

 with others ; and the question arises, 'Is a general trinomial 

 system of nomenclature to be preferred for these, the specific, 

 or binomial term being rigorously restricted to those promi- 

 nent types that are the highest result of evolution in their 

 own particular sphere?' Such a proposal has many advocates ; 

 and I am prepared to go thus far with them, in signalizing 

 certain leading colour varieties and other aberrations from 

 the types, either in form or some other peculiarity, of which, 

 in the course of long investigation, I have seen the frequent 

 recurrence. I agree entirely with the late Dr. Gwyn Jeffreys' 

 remarks (/. of Conch. III., p. 234): " Until an International 

 Court has been established to decide the long-mooted 

 question of not only what is a species, but also what are the 

 limits of so-called species, it is useless to do more than 

 argue it. Every naturalist has a perfect right to his own 

 opinion, and time will be the only test of such opinions 

 being correct or erroneous." 



But if excessive latitude were given to such a trinomial 

 system, there would be great fear of a too minute critical 

 differentiation, especially in genera that ' sport ' more than 

 do the Cowries. Any conchologist, for instance, who has 

 perused Mr. Marrat's researches on the genus Nassa,* in 

 which are enumerated no less than 1,321 links by which the 

 whole is bound together, would shrink from the task at 

 being called upon to bestow appellations upon such a vast 

 concourse (there having been hitherto only 250 recognised 

 commonly), and thus the literature of the subject would 

 become wofully embarrassed, and clogged with such a 

 plethora of dog-Latin, as almost to deter the student of the 

 future from voluntarily entering upon so formidable a study. 



*On the Varieties of Shells belonging to the genus * Nassa,' by F. P. 

 Marrat, Liverpool, 1 880. 



