SIPHONARIA. 



TESTA ovata, depresso-conica; subtus concava: 

 vertice subobliquo, postice recurvo: impressio 

 muscularis anticfe capite, et lateraliter canali 

 interrupta; ad extremitates paulum expansa. 



In general form and appearance tliis new Genus approaches 

 very nearly to Patella, with which it has hitherto heen 

 united by all authors; its lateral canal, and the vertex 

 being obliquely turned backwards^ may be considered as 

 its principal distinguishing characters, separating it not 

 only from Patella, but from Emarginula, whose canal is 

 anterior, and vertex posterior. The animal inhabitant of 

 one species of this Genus appears to have attracted the 

 attention of Adanson, who has shown that it differs ma- 

 terially from that of Patella, and agrees more nearly 

 with that of Kmarginula and Fissurella, particularly in 

 the situation of its branchiae. Adanson's Mouret and the 

 commonly called Patella Sipho, may be regarded as typical 

 species of this Genus. 



Shell ovate, above rather depressedly conical, be- 

 neath concave; vertex, when not eroded, obliquely 

 turned backwards, exactly in the? opposite direction to 

 the canal, which is on the right side. Within, the 

 muscular impression is observable, it is commonly very 

 distinct, and nearly surrounding the inside at rather less 

 than half way from the edge to the lowest point; inter- 

 rupted in front by the bead of the animal, and on one 

 side by the canal, so that between the canal and the head,^ 

 there is an irregularly suborbicular muscular impression 

 only connected witb that of the other side of the shell by a 



