FAMILY SIPHONID — SPIRULA. 55) 
FAMILY SIPHONID. 
Animal little known, with ten or more arms surrounding the mouth. Shell frequently spiral, 
many-chambered, connected by a siphon or tube external or partially covered by the 
animal, 
GENUS SPIRULA. Lamarck. 
Animal purse-shaped, surrounding partially a shell in its posterior part. Head with ten arms 
furnished with suckers ; two of these pedunculated and contracted. Shell spiral, discoid, 
with the turns separated from each other. The siphon on the internal border. 
SPIRULA PERONII. 
PLATE XXXV. FIG. 332. 
Nautilus spirula. Linn. Syst. Nat. 
S. australis. Cuv. Régne animal, Vol. 12, p. 12, pl. 5, fig. 8. 
S. peronit, LAMARCK, An. sans vertéb. Vol. 7, p.600. Gouxp, Invert. Mass. p. 317. 
Description. Shell fragile, white or pearly, occasionally yellowish, with two or three 
spiral turns which do not touch each other. ‘The place of the partitions of the chambers 
within are exhibited by circular grooves in the shell. As yet but one species is said to have 
been discovered, common to the Atlantic and Pacific oceans ; it is probable, however, from 
the difficulty of observing recent specimens, that two if not more species exist. The cham- 
bers communicate by a siphon on the interior sides of the turns. Diameter 1:0—1°5. 
The beautiful little shell belonging to this species is occasionally picked up along our shores 
after heavy storms. The nature of this animal was first detected by Peron, and hence we 
are enabled to infer the structure of those which inhabited the numerous fossil shells of a 
similar conformation. Such are the Orthoceratites, Ammonites, Bacculites, Scaphites, Be- 
lemnites, &c. ‘The nature of this work does not admit of their admission here, more parti- 
cularly as they will all be described in the forthcoming work on the fossils of the State of 
New-York, included in the Report on the Natural History of that State. 
Those who are desirous of becoming acquainted with the numerous fossil shells of the 
United States belonging to this order, will find abundant materials in the American Journal 
of Science, Annals of the Lyceum of Natural History of New-York, Journal of the Aca- 
demy of Natural Science of Philadelphia, and in a volume published by Lea, entitled 
“Contributions to Geology.” 'To those who wish to study the structure of the animals of 
this order, we would refer to the Memoirs of Messrs. Owen and D’Orbigny on this subject, 
and to the Bridgewater Treatise on Geology and Mir cralogy by the English professor Buck- 
land. 
