President's Address. 73 



giiislied I)(ilgian P.'ihoontologist to be greatly strengthened 

 by the structure of the genus Tremanotus (Hall). In this 

 shell, which otherwise has the form of Bucania, there is 

 along the middle of the dorsal side " a row of isolated oval- 

 siphonal openings." Closely allied, if not identical with this, 

 is the genus Salpirir/ostoma (F. lioemer), in which there is one 

 elongated dorsal aperture on the body whorl, but distant 

 from the outer lip. Mr Meek concluded his interesting re- 

 marks thus : — " Now we have no examples, so far as known 

 to the writer, either amongst the Ileteropoda or Cephalopoda, 

 living or extinct, of a shell with isolated siphonal openings, 

 while we have many such examples amongst the Prosobran- 

 chiate Gasteropoda, — such for instance as the Haliotidie, 

 FissurellidiB, and Pleurotomariidoe — the bearing of this 

 feature in the newly-discovered type has on the question 

 respecting the affinities of the Bellerophonticla3, will be 

 readily understood. In other words it indicates for the 

 family a position near the Fissurellidte and Haliotidiie, and 

 betw^een those groups and the Pleurotomariidoe."* 



In these remarks I cordially concur, and following the re- 

 searches of Messrs De Koninck and Meek, would suggest the 

 transfer of Belleroylion and the allied genus Porcellia to the 

 systematic position assigned by these writers. 



The genus Porcellia (Ldveille) has a depressed discoidal 

 form, with the whorls in one plane, with the exception of the 

 nucleus, which is spiral. The umbilicus is large and open, ex- 

 posing all the whorls. The outer lip is medionally divided 

 by a sinus, represented along the dorsal line by a groove. 

 The genus differs from Bcllero2ohon chiefly in its thin 

 shell, depressed form, and highly ornate surface. One 

 species only is met with in the Carboniferous rocks of 

 Scotland, P. armata (De Vern.), a characteristic shell of 

 the Ptussian Carboniferous limestone, whilst, strange to say, 

 the species found in the English Carboniferous limestone, 

 P. Woodivardi (Martin, sp.), has not been met with there. 



In addition to the shells we have discussed in their 



* Meek, loc. cit. Dr Waageii also arrives at pretty much the same conclu- 

 sions (ojj. cit., p. 129). 



