Mr. C. P. Sigerfoos on the Pholadide. 233 
In both the adult females that I have examined there is no 
trace of the ridged hollow on the abdomen, and the only trace 
of the tooth on the pedicelvis a slight angulation of the dorsal 
sclerites. The absence of the organ in the female and the 
high development that it attains in the male permit us to 
conclude that the sound emitted is used as a sexual call. 
XXXIV.—The Pholadidew : Note on the Early Stages of 
Development. By C. P. StGERFoos *. 
Durine the summer of 1894, while with the Johns Hopkins 
Marine Laboratory at Beaufort, I was employed by the 
U.S. Fish Commission to study the natural history of the 
ship-worms on account of their great economic importance. 
While so engaged I observed the early stages in the develop- 
ment of four species of the Rholadide; these were Pholas 
truncata, Teredo navalis, T. norveyica, and T. (Xylotrya) 
jimbriata. T. navalis is the common ship-worm of Europe, 
and has been frequently studied. It is found but sparingly 
at Beaufort, and is of little economic importance there. The 
from Chatham Island, is the male example that Mr. Cambridge has 
figured in the ‘ Transactions of the New Zealand Institute,’ 1878, p. 202; 
the second is the female from Canterbury, the type of C. fasciata, 
L. Koch; and the third is an additional female from Waikato, which 
Dr. L. Koch also examined and identified. Koch’s type is an adult 
female ; but since its carapace measures only a little over 3 millim. in 
length, I find it hard to believe, without further evidence, that the male 
from Chatham Island, which has the carapace 10°5 millim. long, is co- 
specific with it. It uppears to me too that the second female, the one 
from Waikato, is also distinct from fasciata, since it is of considerably 
larger size (carapace 6'5 millim. long), and the impressions on the vulva 
have a different form. I may add that in both of them there is a very 
distinct tubercular tooth (omitted from Koch’s figure) at the anterior end 
of the median groove of the vulva; that the anterior lateral eyes in 
C. fasciata are round, and only oval, as Koch has figured them, when 
seen in perspective ; that the posterior spiracles are in front of the colulus, 
and are not placed in the integumental fold that Koch mentions and 
compares with that of Anyphena; and that the additional stigma that 
Mr. Cambridge figured and described is a muscular scar. 
Two species, then, of the genus have been described, namely Cam- 
bridyea antipodiana (White) (P. Z. 5S. 1849, p. 5), with which C. fasciata, 
Cambr. (Tr. N. Z. Inst. 1873, p. 202), is synonymous, and C. fasciata, 
L. Koch (‘Die Arachn. Australiens,’ i. p. 358, pl. xxviii. fig. 2, 1871). 
These two must, I think, be provisionally regarded as distinct, on account 
of the enormous disparity in size between the two sexes, the male being 
so very much larger than the female. 
* From the ‘Johns Hopkins University Circulars,’ vol. xiv. no. 119, 
pp. 78, 79. 
