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Records of the Australian Museum (2017) Vol. 69 
Figure 9. Janthina egg capsules. (A) Janthina umbilicata d’Orbigny 
(copy of Laursen, 1953: fig. 27). (B) Janthina globosa (Swainson) 
(copy of Laursen, 1953: fig. 31, reduced). Scale bars 1 mm. 
egg capsules of Janthina species are ovate-triangular and 
translucent, with fine spines around the exterior of the wider, 
convex, distal end (Simroth, 1895: pi. 1, figs 24—26; Laursen, 
1953: figs 23, 27, 31, 37; Okutani, 1956: text-fig. 2; Rolan 
& Trigo, 1973: figs 4-5; Fig. 9), so they resemble the egg 
capsules of neogastropods. The capsules of Recluzia species 
have not been described in detail previously. The capsules 
of both R. lutea and R.johnii are shown by the illustrations 
by Bennett (1966: pi. 11, fig. 1), Churchill et al. (2011b: 
figs 1B-C) and here (Figs 6-7) to be significantly simpler 
than those of Janthina , without spines, slightly brownish 
dull yellow in colour, more opaque and a little longer and 
narrower than those of Janthina , and cylindrical with a 
hemispherical distal end. 
The exception is Janthina janthina , which broods its 
eggs to the veliger stage in the oviduct, releasing veligers 
into the sea. The description by Wilson & Wilson (1956: 
302; see paragraph below) of the release of veligers by J. 
janthina expressly mentioned the release of packets, which 
almost immediately opened to release individual veligers. 
Cross-sections of oviducts of J. janthina shown by Laursen 
(1953: figs 5-7) closely resemble those of J. exigua (Laursen, 
1953: fig. 3). This implies that at least some remnant of 
capsule formation is retained in J. janthina. ; eggs evidently 
are enclosed in capsules before release in all species, and 
ephemeral transparent capsules enclosing the veligers are 
retained in J. janthina. The egg capsules of most Janthina 
species and, in J. janthina , packets of veligers are released 
on the left (inhalant) side of the mantle cavity, as the right 
side is blocked by the right epipodium (Wilson & Wilson, 
1956; Fretter & Graham, 1962: 563; Bayer, 1963: 460) and 
simply by the shell. The egg capsules of neustonic Epitoniidae 
contrast strongly with the long chains of many small, roughly 
spherical to tetrahedral, sand-agglutinated egg capsules 
joined by chalazae that are produced by benthic Epitoniidae 
(e.g., Bennett, 1966: pi. 9, fig. 2; pi. 10, figs 1-2; pi. 11, fig. 
1; Robertson, 1983, 1994; Pastorino & Penchaszadeh, 1999; 
Gittenberger & Gittenberger, 2005). McDermott (1981) 
described the elongate, cylindrical but still linked, rough¬ 
surfaced capsules of Epitonium rupicola (Kurtz, 1860). The 
capsules of Janthina and Recluzia are not linked by chalazae, 
an obvious adaptation to life attached to a bubble float, as long 
chains of egg capsules would be impractical for neustonic 
gastropods. The chalazae of benthic Epitoniidae are tough, 
elastic mucus threads secreted by the pedal mucus gland, rather 
than being secreted by any structure in the oviduct (Bennett, 
1966; Robertson, 1983: 6; Gittenberger & Gittenberger, 
2005: figs 264-299). Therefore, there is no difference in 
origin or composition between the bubble float of Janthina 
and Recluzia and the chalazae of benthic Epitoniidae; their 
pedal mucus glands merely are adapted to secrete differently 
shaped products. Formation of a bubble float is an unexpected 
adaptation for an epitoniid, but it does not provide a radical 
character that precludes the classification of Janthina and 
Recluzia in Epitoniidae. Indeed, Churchill etal. (2011a: 802) 
viewed the bubble float of Janthina and Recluzia as a modified 
epitoniid egg mass, providing a helpful perspective on the 
evolution of the floating habit. 
Wilson & Wilson (1956: 302) described the shedding of 
larvae by Janthina janthina. They reported that “In the later 
part of the day after [the Janthina specimens were collected], 
one animal shed singly at intervals at least thirty-six dark 
brown cylindric pellets, [each] about 1/10 in. [2.5 mm] long 
... They fell to the bottom of the container ... and quickly 
disintegrated, releasing a number of fully developed veliger 
larvae with brownish purple shells, swimming with a bilobed 
velum. Twenty or more were in each packet, varying from 
100 to 230 pm across the shell at its maximum width. ... 
As a prelude to the shedding of a packet the propodium 
was withdrawn from its normal resting position appressed 
to the base of the float, and was furled up and twisted from 
side to side. ... Extrusion was so rapid that it could be 
missed ... from between the bottom of the foot and the gills 
a “little bullet” suddenly shot upwards and out over the 
(morphologically) left-hand side of the shell, that which is 
not covered by the epipodium ... Several packets were seen 
shortly after emergence and there was no doubt that they 
came out from this side. ... [T]he next day, when it was less 
active ... a small number of veligers emerged singly at their 
own pace”. The larvae were neither geotaxic nor phototaxic, 
but gyrated actively over the bottom of the container. Bayer 
(1963: 460) similarly described the ejection of a pellet about 
3x4 mm, which fell to the bottom of the dish, and after about 
five minutes disintegrated to form a small heap of larvae that 
dispersed rapidly. 
