226 REPORT ON ZOOLOGY, MDCCCXLIII. 



costae. Mistaken Island. H. semiplicatu, id., anteriorly, 

 longitudinally plicated. 



The French species of Emarginala have been described by Rccluz, in the 

 'Rev. Zool.,' and tlie synonymy cleared up. They are as follows : E.fissura, 

 Lam., Icevis, rosea, Bell, Hazardi, Payr., elongata, Costa, fi&surata, Sowerb., 

 franciscana, Rccluz, new species. 



Fissurella reticulata is distinguished as a species from F. grteca, by 

 Recluz. (Rev. Zool. p. 110.) F. occitanica, id. (ib.) F. oblonga, Menke, 

 rose-coloured. 



Fissurella (Rim-ula) striata, Recluz. (Rev. Zool. p. 228.) 



Cyclobrancliia. Patella onycMtis and insignis, Menke, of 

 which the latter in his opinion is the forgotten P. cruciata, 

 L. Chiton biradiatus, Sowerby, from the Philippines. (Proc. 

 p. 102.) 



CONCHIFERA. 



D'Orbigny has considered the question of the natural 

 position of the bivalve Molluscs. Linnaeus, Bruguiere, and 

 Lamarck place the hinge inferiorly, Blainville reverses the 

 position, and places it superiorly, Deshayes assigns an infe- 

 rior position to the siphons and a superior one to the mouth. 

 D'Orbigny would now, in the symmetrical Conchifera, pro- 

 pose the last possible position that remains for these organs, 

 and would make the siphons superior and the mouth infe- 

 rior, because in its natural position the animal assumes a 

 posture corresponding to this. It is undoubtedly true that 

 in the living Conchifer the siphons are extended upwards 

 and the mouth directed downwards, but not in such a way 

 as that these organs should assume a perpendicular position, 

 for the siphons are directed upwards and backwards. I am, 

 consequently, unable to agree in opinion with D'Orbigny. 

 The natural position of the Conchifera is between the per- 

 pendicular and horizontal. In consequence of the animal's 

 pushing itself forward in the sand by means of the fleshy 

 foot, the position approaches much more nearly to the hori- 

 zontal, so that it is evident that unless we carry accuracy so 



