President's Address. 57 



Touching the supposed identity of Sanr/icinolites and Al- 

 lorisma the late Dr Stoliczka says, " we can say again that 

 unless King's statement and apparently correctly executed 

 figures are disproved, the identity of the two genera must 

 be set aside as inadmissible."* By the same author San- 

 guinolites is placed in the Solemyida'., but it remains to be 

 seen if any hinge teeth are present. 



Allorisma, as originally defined in 1844,-|- unfortunately 

 contained species of both the last-mentioned genera, but in 

 1850 J Professor King properly restricted it, and in this form 

 it becomes, I believe, one of the best defined in the British 

 Carboniferous rocks. 



Like Sanguinolites the shells of this genus are traversely 

 elongated, equivalve, and edentulous, but with an external 

 ligament. Furthermore the beaks are very anterior, almost 

 terminal, and the pallial line is sinuated. Externally the 

 surface of the valves is granulated. By some writers it is 

 considered identical with the secondary genus Mijacites, but as 

 pointed out by Messrs Meek and Hayden,§ the edentulous 

 nature of the hinge in Allorisma necessitates their separation. 

 Finally, it is not improbable that Allorisma, Sanguinolites, and 

 Mdmondia, hitherto all placed in the Anatinidce, are members 

 of distinct families. 



One or two other unimportant genera are said to occur in 

 Scotch Carboniferous rocks, but they do not require any 

 special notice. 



The foregoing sketch has been drawn up, not as an exhaus- 

 tive epitome of the Carboniferous Bivalves, but rather as an 

 indication of some of the difficulties which will have to be 

 met and unravelled before a Monograph of this important 

 class can be written. 



The Gasteropoda, or Univalve shells, like the preceding 

 Class of Bivalves, are sadly in want of revision. The re- 

 marks made on the latter are equally applicable here, and 

 may be as justl}^ carried over to the Cephalopoda. 



The chief works at present available for the study of the 



* Pal. Indica, p. 270. f Annals Nat. Hist., 1844, xv., \\ 315. 



X Mon. Term. Foss., p. 19G. g Pal. Up. Missouri, p. 37. 



