16 
On the Anatomy of Spirilla australis, Lamarck. 
on dorsal part of mantle; i, funnel projecting between tlie pair 
of pointed lobes on the ventral side of the fore border of the 
mantle. Nat. size. 
Fi(j. 2. Dorsal view of hind part of mantle, showing the interspace 
between the two terminal umbilical lobes (c, c ). A portion of 
the outer whorl of the shell is exposed, at Zi, by removal of the 
periostracum (g) , with which the epithelial layer of the mantle 
(/) is continuous. Magnified 3 diameters. 
Fig. 3. Terminal disk (ab) and appendages (etc), with ends of terminal 
lobes (c, c), of the mantle, and exposed parts of outer whorl of 
shell (h, Zt) . Magn. 2 diam. 
Fig. 4. Muscular mass of Spirula , including the head and its appendages 
(i, 2 , 3 , 4 , and d), the funnel (i), the'pallial valve (/*), the retrac¬ 
tors of the head (/) and funnel (t), which blend together to be 
attached to tlie last chamber of the shell (u); the digestive 
organs and ink-bag are also given. Nat. size. 
Fig. 5. Anterior view of the head and appendages, with the mouth and 
bases of the peduncles. Nat. size. 
Fig. 6. One of the eight arms, showing the acetabuliferous surface. 
Magn. 3 diam. Three detached acetabula (b, cl, e) and their 
pedicles, more highly magnified. 
Fig. 7. Mouth and bases of the cephalic arms and peduncles, with the outer 
lip laid open, exposing the inner lip and mouth. Magn. 3 diam. 
Fig. 8. The buccal mass. Magn. 4 diam. 
Fig. 9. The upper and lower mandibles. Magn. 6 diam. 
Fig. 10. Muscles of the buccal mass, upper salivary gland, and tongue. 
Magn. G diam. 
Fig. 11. Parts of Spirula, extending from tlie mouth (n) to the shell (s, v), 
magn. 3 diam.: the letters are explained in the text. 11", inner 
surface of inner lip. 
Plate II. 
Fig. 1. Dissection showing the funnel and its retractors, gills, a nidamen- 
tal gland, ovary, and part of the shell. Magn. 3 diam. 
Fig. 2. Dissection of parts of Spirula , from the mouth (m) to part of the 
shell (r); the letters are explained in the text. Magn. 3 diam. 
Fig. 3. Head of Spirula, with pallial valve and muscles, and female 
organs of generation. Nat. size. 
Fig. 4. Parts of Spirula, including the lower salivary glands, liver, and 
contents of last shell-chamber. Magn. 3 diam. 
Fig. 5. Muscular mass of retractors of head and funnel of Spirula, and 
their attachment to the last shell-chamber. Nat. size. 
Fig. 6 . Acoustic organs and contiguous parts. Magn. 4 diam. 
Fig. 7. Digestive organs. Magn. 4 diam. 
Fig. 8. Shell of Spirula, with hemispheric mass filling terminal shell- 
chamber, raised ; also part of mantle and terminal disk. 
Fig. 9. Terminal chambers of shell, laid open to show origin of siphon 
and contents of last chamber. Magn. 2 diam. 
Plate III. 
Fig. 1. Female organs and funnel. Magn. 3 diam. 
Fig. 2. Alimentary canal, hepatic lobes, interior of funnel, and last shell- 
chamber. Magnified. 
Fig. 3. Circulating and respiratory organs. Magn. 
Fig. 4. Digestive organs ; mass of retractor muscles. Magn. 
Fig. 5. Portion of oviduct, with left gill and branchial heart. Magn. 
Fig. G. Termination of oviduct with oviducal gland. Magn. 
