Studies on Spawning Behavior, Egg Masses, and Larval Development 
in the Gastropod Genus Conus , Part I 
Observations on Nine Species in Hawaii 1 
Alan J. Kohn 2 
This REPORT deals chiefly with the character- 
istics of egg masses and the course of larval de- 
velopment of gastropod mollusks of the genus 
Conus , based on material collected in the Ha- 
waiian Islands during 1954-56, while the. au- 
thor was at the Hawaii Marine Laboratory. 
Some information has been obtained on 9 of 
the 33 species of Conus known to occur in the 
Hawaiian archipelago (Kohn, 1959^). 
Bergh stated (1895: 100), "Ueber Paarung, 
Eilegen und Laich der Coniden ist . . . absolut 
nichts bekannt.” 
The only reference prior to that date which 
has come to the attention of the present writer 
is an extremely brief description of the oothecae 
or egg capsules of C. capitaneus Linnaeus by 
Adams and Adams (1853: 5). Cooke (1895) 
and Hornell (1922) figured egg capsules of 
unidentified species of Conus , but Lamy 
(1928), in an extensive study of prosobranch 
egg capsules, noted their similarity to those of 
other genera. These early figures cannot be as- 
signed with certainty to Conus , and Bergh’s 
statement remained essentially correct until Pe- 
tit and Risbec (1929) and Risbec ( 1931, 
1932) described the egg masses and develop- 
ment of four species of Conus from New Cale- 
donia. Subsequently, similar information on six 
additional species has been reported by Thor- 
son (1940), Persian Gulf; Lebour (1945), 
Bermuda; Knudsen (1950), West Africa; Na- 
tarajan (1957), India. More recently Lewis 
(I960) has provided additional information on 
the egg capsules and larvae of C. mus Hwass 
in Bruguiere, a species discussed also by Lebour 
(1945). 
Ostergaard (1950) described the spawning 
and development of six species of Conus in Ha- 
1 Contribution No. 148, Hawaii Marine Laboratory. 
Manuscript received February 8, I960. 
2 Department of Biological Sciences, Florida State 
University, Tallahassee. 
waii. The present paper provides information 
on five additional species and notes on develop- 
ment in one species mentioned by Ostergaard 
but not studied in detail by him. 
Most of the material was collected on coral 
reefs which fringe much of the Hawaiian coast- 
line and provide suitable spawning sites for a 
number of species of Conus (Kohn, 1959^). 
Bouin’s solution and 10 per cent sea water 
formalin were used as fixatives. Except where 
stated otherwise, all material was collected by 
the author, and the numbers used to identify 
specimens are those of the author. The pre- 
served egg capsules and embryological material 
have been deposited in the University Zoolog- 
ical Museum, Copenhagen. 
GENERAL CHARACTERISTICS OF SPAWNING 
AND EGG MASSES 
As is typical of the higher prosobranch gas- 
tropods, the sexes are separate and fertilization 
is internal. The prominent penis of the male is 
a flattened muscular tube which arises from the 
right side of the dorsolateral body wall just be- 
hind the head and is rounded or pointed at 
the tip (Bergh, 1895: 97, figs. 4, 5, 76, 149, 
159). 
In copulation, it is inserted into the vagina 
of the female, which is located anteriorly at 
the extreme right edge of the mantle cavity, 
where the mantle joins the body wall, and ad- 
jacent to the anus (unpublished observations). 
A detailed account of the genital apparatus of 
prosobranchs has been given by Fretter (1941, 
1946). 
Although the process of oviposition in Conus 
has not been studied closely, it is essentially 
similar to that first described in other higher 
prosobranchs (Order Neogastropoda) by Cun- 
ningham (1899) and later amplified by Ankel 
(1929), MacGinitie (1931), and Ino (1950). 
Eggs surrounded by albuminous, probably nu- 
163 
