38 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



criticized, for to be of any value the suggested nomination must be 

 usable with wide limits. In some cases even subspecific distinction 

 has been denied such forms, in others full specific value unhesitatingly 

 accepted. The two extremes are probably incorrect, as the first is 

 too little, and the second does not indicate any close relationship 

 whatever. A mean course is the valuable one desired, and I would 

 recommend the following method as available and suggestive. 



For the littoral geographic forms I advise the usage of simple 

 trinomials such as in common use in other classes, so that with this 

 method we would be in agreement with usual conditions. For the 

 deep-water forms I propose to continue the usage of a trinomial 

 with a plain bracket enclosing the second name. For the fossil 

 forms corresponding as closely as to be recognizable as of apparently 

 direct lineage I would use again a trinomial, but in this case use 

 a square bracket for the second name. To illustrate we will regard a 

 special case which is partly true and partly fictitious. A shallow- 

 water Sydney shell was named Turritella sinuata, Reeve. From 

 38-40 fathoms in Bass Straits, Watson named Turritella runcinata, 

 T. accisa, and T. cordismei. Verco has regarded accisa as a deeper- 

 water species than runcinata in South Australia, and I have suggested 

 that runcinata is the deep-water form of sinuata, while cordismei 

 is the shallow-water form in Bass Straits. A fossil species called 

 T. jplatysjoira, Tate, seems the ancestral form of sinuata. Grranting 

 these premises, I propose to show the facts by such a nomination as 

 the following : — ■ 



T. sinuata sinuata, the Sydney shallow-water form. 



T. siniiata cordismei, the Bass Strait shallow-water form. 



T. (sinuata) runcinata, the Bass Strait deej)er-water form. 



T. [runcinata) accisa, the South Australian deep-water form. 



T. [sinuata'] platyspira, the fossil representative. 

 By this means the specific distinction is not impugned but the 

 comparative relationship is expressed. The simplicity of this 

 scheme is apparent, and the only argument against it is that I am 

 suggesting a trinomial nomenclature instead of a binomial. I agree 

 to this, but point out that the binomial scheme is incapable of 

 expressing a series of relationships such as I have here outlined. 



