52 JOURNAL OF CONCHOLOGY, VOL. ID, NO. 2, Al'RIL, I90I. 



hinge-line along the dorsal margin. Nor did we observe in the speci- 

 mens before us any transition between the external markings of the two 

 forms. In every case the two were most readily separable. Perhaps, 

 however, Mr. Marshall has specimens which will throw further light 

 on the subject ; if so we trust he will kindly favour us with a sight of 

 them. 



There is some evidence to show that confusion has arisen from 

 collectors, unfamiliar with the true T. geographicus, having distributed 

 some varieties of T. pidlastra as T. geographicus. Thus, in the 

 British Museum there is a tablet (in a small collection presented by 

 McAndrew) marked " T. geographicus, S. coast of Spain," bearing 

 three specimens, each belonging to a different species, and in Jeffreys' 

 handwriting in pencil ; the right and left-hand specimens are respec- 

 tively marked off as T. virgivea and T. pidlastra. Messrs. Sowerby 

 and Fulton, too, have kindly shown us three sets of specimens, all 

 received from one source, and all labelled " T. geographiais" of \sh\c\\ 

 one set alone was correctly named, the other two being manifestly 

 varieties of T. pullastra. 



Both Pfeiffer and Roemer, who, to put it mildly, were at least as 

 good conchologists as Jeffreys, considered the two forms distinct, but 

 identified T. pullastra with T. senegalensis Gmelin (Linn. Syst. Nat., 

 ed. 13, p. 3, 282, no. 67), and were this determination upheld, those 

 who contend for the identity of the two forms have no choice but to 

 accept this name, since it occurs earlier in the work cited than that ot 

 T. geographicus by eleven pages ! Adanson's figure and description, 

 however, to which Gmelin refers, are far too meagre and unsatisfactory 

 to render this identification certain (though Bucquoy, Dautzenberg, 

 and Dollfus adopt the species as distinct, and give a figure which 

 approaches that of Adanson^) whereas there can be no doubt as to 

 Montagu's T. pidlastra. 



Bucquoy, Dautzenberg, and Dollfus, on the other hand, consider 

 T. geographicus to be a variety of T. pullastra^ though they give no 

 reason for it, and the two forms are instantly separable in their excel- 

 lent plates ; probably they simply follow Jeffreys. 



Anyhow, as matters at present stand, the form T. geographicus 

 appears so clearly marked off in its shape, coloration, and geographical 

 distribution, as to be worthy to rank as specifically distinct from T. 

 pullastra. 



I Moll. Marins Roussillon, vol. 2, pi. 42, fig. 2. 



