86 
PACIFIC SCIENCE, Vol. IX, January, 1955 
which were taken from the adjacent rock 
surface. Some of the egg masses were pre- 
served in formalin and Bouin’s fluid, three 
were placed in a glass tube which was plugged 
with damp cotton wool. Ten days later at 
Christchurch when the tube was opened sev- 
eral larvae had hatched. The contents of the 
tube were transferred to a finger bowl of sea 
water and the larvae remained alive for 9 
weeks, during which time about 20 hatched. 
Many of the newly hatched larvae were found 
just above the water line on the side of the 
finger bowl. 
DEVELOPMENT 
The egg masses are roughly circular or oval, 
about 12 mm. in diameter and 6 mm. in 
height. (Fig. la, b). Each rather tough, gela- 
tinous, transparent egg mass contains from 
9 to 35 ovoid egg cocoons, filled with a yel- 
lowish albumen. The cocoon wall is tough 
and in many cases the fixative penetrated 
poorly. After staining with Gower’s acetic- 
alum carmine and clearing it was found that 
some of the cocoons contained early larvae, 
the earliest stage present being an advanced 
veliger 0.14 mm. long, in an egg capsule 2 
mm. in its greatest diameter (Fig. id). Be- 
cause of the poor fixation details of the struc- 
ture of the veliger could not be seen, parti- 
cularly the structure of the shell which had 
collapsed and crumpled in all the specimens 
examined. However, it was possible to see 
that the veliger (Fig. le) is provided with a 
well-developed, ciliated, bilobed velum. 
The veliger stage is passed within the egg 
mass, the larva hatching in the crawling stage. 
The next stage present was a post veliger 
0.60 mm. long (Fig. 1 h). From this stage 
there is little change in structure apart from 
increase in size. When the larvae leave the 
egg masses they are approximately 1.5 mm. 
long, quite colourless except for two black 
eyes (Fig. if, /'). The shell is homy, brownish, 
semi-transparent with well-marked growth 
rings (Fig. 1 g). 
The smallest individuals taken from the 
adjacent rock surface were 4.5 mm. long (Fig. 
1 j,k). A random sample of 34 individuals 
gave the following size distribution: 
Length (mm.) Number 
4 . 5 - 5.5 6 
6 . 0 - 7.0 0 
7 . 5 - 8.5 7 
9 . 0 - 10.0 0 
10 . 5 - 11.5 5 
12 . 0 - 13.0 4 
13 . 5 - 14.5 8 
15 . 0 - 16.0 4 
The largest individual found in the colony 
was 15.5 mm. long. 
DISCUSSION 
Hubendick (1946) lists some 60 species 
belonging to the Siphonariidae. He recognizes 
2 genera, Williamia, with 4 species, and St- 
phonaria , with 59 valid species. On the basis 
of comparative anatomy he divides the Genus 
Siphonaria into 10 natural groups, namely, 
Liriola , B achy siphonaria, Benhamina , Kergue- 
lenia , Patellopsis , Simphisiphonaria , Ductosiphon- 
aria, Heterosiphonaria , Sacculosiphonaria , and 
Siphonaria . Other workers consider some of 
these as genera. 
There appears to be confusion concerning 
the status of some of the New Zealand species 
of Siphonariidae. Powell (1946), following 
Suter (1913—15) recognized three genera and 
five species for New Zealand, Siphonaria aus- 
tralis Quoy and Gaimard, Siphonaria cookiana 
Suter, Siphonaria zelandica Quoy and Gaimard, 
Benhamina obliquata (Sowerby), and Kergue - 
lenella stewartiana (Powell). Hubendick, how- 
ever, did not recognize S. zelandica as a sep- 
arate species considering it to be a synonym 
of S. australis . An examination of shell char- 
acters and genitalia of specimens from many 
localities has shown that there are three spe- 
cies of Siphonaria in New Zealand. S. zelandica 
appears to be a distinct and valid species and, 
as Powell (1946) noted, the specimens as- 
signed by Hubendick to S. ( Simphisiphonaria ) 
cookiana belong to S. zelandica , since the gen- 
