44 Mr.J.C. Pearce on the Embryo of an Ichthyosaurus. ) 
and margins having a tinge of red. Legs long, robust, provided 
with hairs and sessile spmes; fourth pair the longest, then the 
first, third pair the shortest; they are of a reddish brown colour. 
Each tarsus is terminated by three claws ; the two superior ones 
are curved and pectinated, and the inferior one is inflected near 
its base, on each side of which are two or three fine teeth. The 
palpi resemble the legs in colour. Abdomen oviform, thickly 
covered with hairs, convex above, projecting over the base of the 
cephalo-thorax; along the middle of the upper part extends a 
broad, dentated, yellowish brown band, on each side of which is — 
a brownish black band; sides and under part yellowish brown ; 
the former is spotted with brownish black, and a broad, dark 
brown band extends along the middle of the latter. Superior 
spinners long, slender, hairy, with the spimning-tubes disposed 
along the under side of the terminal jot. The sexual organs 
exhibit an orifice having a red-brown margin. Plates of the 
spiracles dull yellow. The body and limbs are supplied with 
numerous compound, sessile hairs. 
The male is smaller than the female, but resembles her in co- 
lour and in the relative length of its legs. The cubital and ra- 
dial joints of the palpi are short ; the former is not provided with 
an apophysis, but the latter has a large, obtuse one at its ante- 
rior extremity, on the outer side; the digital joint is oval, but 
elongated, the extremity being slender and compact; it is con- 
vex and hairy externally, concave within, comprising the palpal 
organs, which are highly developed, complicated im structure, 
-with a large, spiral spme, brownish black on the outer and pale 
yellow on the inner side, which is very prominent and recurved 
at its extremity, and a strong, dark reddish brown process at the 
outer side projecting beyond the margin of the digital joint. 
I have named this handsome species in compliment to Richard 
Potter, Esq., M.A., Queen’s College, Cambridge, and Professor 
of Natural Philosophy in University College, London, through 
whose friendly zeal in promoting my zoological researches I have 
been supplied not only with the spiders introduced to notice in 
these pages, but also with numerous specimens of British species. 
(‘To be continued. | 
VIII.— Notice of what appears to be the Embryo of an Ichthyo- 
saurus in the Pelvic cavity of Ichthyosaurus (communis f). 
By J. Cuanine Prarce, F.G.S., M.R.C.S. 
In developing an Ichthyosaurus which I took up from the rock 
in the brown laminated lias clay of Somersetshire, and having 
reversed the animal so as to lay bare that surface which was 
