3 
of Spirula australis, Lamarck. 
thin epithelium (f) is continued upon, and seemingly lost in, 
the periostracum (g) ; part of the shell is exposed at /«, fig. 2. 
The well-defined convex border of each lateral posterior or 
terminal lobe (c) of the mantle has its smooth, soft, inner layer 
tucked up, as it were, and bent towards the central aperture 
of the umbilicus. 
Between the lobes is an elliptical convex substance ( u bouton 
terminal,” De Blainville* ; u thick gland,” Gray f) (fig. 3, 
a b ) with a central depression (ib. a d) ; this disk is flanked by 
a pair of oblong productions (ib. a c, a c), the homologues of 
the better-developed muscular fin-like bodies in Spirula re- 
ticulata\. 
M. de Blainville describes the lateral appendages [a c) as 
fins, u fort semblable a ce qui a lieu dans les Sepioles ” §. 
Dr. Gray, in his account of the original Cumingian specimen 
affirms, “ It differs from the cuttlefish in being entirely 
destitute of fins” ||. It is possible that the French anatomist 
may have had for his subject a specimen of Spirula reticulata , 
in which they are more developed ^j. The parts (a c) in my 
example of Spirula australis may have been contracted ; but I 
deem them, like those in S. reticulata , to be homologues of 
such small terminal lateral fins as one sees in Loligopsis. 
The intervening terminal gland-like mass is composed of a 
substance resembling dense cellular tissue, in which minute 
tortuous filaments were the chief structural character; its 
thin covering was vascular. At the middle of the central 
depression is a pore; but this terminates blindly, and is not the 
duct of a gland. If the disk (a b) were applied to a flat sur¬ 
face and the central part [ad) were withdrawn from the level, 
a vacuum would be produced, which would convert the disk 
into a sucker. Should the Spirula so attach itself, as Bum- 
phius describes, its tentacles (fig. 1, cl) and arms (1,2, 3,4) 
would be free to exercise their prehensile power on any 
passing object of food. The formal analogy to the polype, 
indicated by Aristotle’s name for the “ Poulpe,” would thus 
be carried further in Spirula by its occasional repetition of the 
status of a hungry Actinia. 
The mantle consists of a thin epiderm, a pigmental reticular 
connective tissue, and an unusually dense corium, in which the 
circular or transverse muscular fibres are crossed by thinner 
and more superficial longitudinal fasciculi (PI. II. fig. 2, h h). 
* “ Quelques observations sur l’animal de la Spirule,” Anuales fran- 
§aises et etrangeres d’Anatomie et de Physiologie, tome i. 1837, p. 37G. 
f Annals and Magazine of Natural History, April 1845. 
| ‘ Zoology of the Voyage of H.M.S. Samarang,’ Mollusca, p. 13, 
pi. iv. figs. 3, 9. § Loc. cit. || Luc. cit. 
See my Monograph, loc. cit. pi. iv. fig. 9, a c, a c. 
