49 
he would lay aside, substituting Fistulana for it, not- 
withstanding Spengler’s priority and acknowledged ac- 
curate definition. 'To this plan we cannot subscribe. 
GASTROCHAINA tortuosa. 
TAB. DXXVI.—fig. 1. 
Spec. Cuar. Obliquely lanceolate, twisted. 
Tur longest diameter is four times the united depths of 
the two valves, or above three times the length; the 
hinge line is straight, the remainder of the shell twisted 
almost one turn: the sinus in the edge for the passage 
of the foot is elongated, acute towards the front; the 
whole surface nearly smooth. 
Occurs in a dark brown clayey sandstone much stained 
with iron, in the Cliffs of Robin-Hood’s Bay, near 
Scarborough. The specimen is in the collection of Mr. 
Bean of that place: it consists of one valve placed upon 
the surface of the stone, without any indication of the 
tube that once inclosed it. 
