* 
B * ; 
Mr. Sowrnrsy on the Spiral Tubes in the Terebratula. 515 
Fig. 1. Terebratula striata, Anomia striata of Martyn*. The lower 
valve containing the spiral tubes considerably enlarged, 
the specimen being little more than one inch long. 
a.a. Sections of those parts of the spiral tubes by which 
they are attached to the upper valve. 
b. The place of the triangular aperture immediately 
above the lower beak. 
Fig. 2. Terebratula striata. The two valves with onc end cut off. 
a. The triangular aperture between the beaks. 
b. Section of the spiral tube near the end. 
B suspect Anomia cuspidata}-, Linn. Trans. vol. iv. Pl. 4, with 
the beak of the perforated valve lengthened and reverse, may 
have a similar construction within, as well as Anomia subconica of 
Martyn, tab. 47. 
aa 
Since I presented to the Society a sketch of an Anomia or Te- 
rebratula with a spiral internal cartilage, I have received a species 
of Terebratula of a very different construction with a spiral carti- 
. lage; and I conceive that a figure of this species would be a con- 
venient addition to my former communication, as showing that 
the spiral cartilage is less confined to shells of a certain external 
form than might have been expected. Such as I had seen before 
had straight elongated hinges, and the deeper shell had a trian- 
gular foramen, or distant curved beaks indicating it. The present. 
sketch (fig. 3, 4.) represents a shell curved laterally from the 
hinge, which must bé very short, the beaks very small, and with- 
out any space for a triangular foramen externally, although within 
* Mr. Martyn sent me this specimen some years since. It shows the triangular aper- 
ture, although his figure does not ; but the shell showed no sign of the tube till I broke it 
for information. 
T Figured, since the pU of this Paper, as T cupid in Mineral Concho- 
logy, tab, 120. 
VOL. XII. 9x there 
