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POPULAR SCIENCE REVIEW. 
THE STEUCTUKE AND AFFINITIES OF THE 
SEA-SQUIETS [TUNICATA]. 
By JOHN CHARLES GALLON, M.A. (Oxon.), F.L.S., 
: Lecturer on Comparative Anatomy at Charing Cross Hospital. 
^^Profecto enim a summis molluscis ad infima zooplijta, ^ Natura non 
facit saltum.’ ” — Chamisso. 
HOUGH the animals which are the subject of the present 
article are well known to the naturalist, they are by no 
means familiar objects to the ordinary sea-side rambler ; partly 
because some members of the order are oceanic, in part for the 
reason that those which are inhabitants of our coasts are either 
unattractive in appearance, or, if better-favoured, are concealed 
by rocks and the fronds of sea-weeds. 
Some, however, of our readers, when wandering along the 
edge of a shore strewn with the litter of a recent storm, count- 
ing the dewy pebbles, fix’d in thought,” may perchance have 
stumbled across a curious object, combining the consistency of 
leather with the appearance of a lump of dirty ice, to which, 
maybe, sticks an empty sh el 1-valve, a mass of pebbles, or a root 
of tangle. This, after being handled, is very probably squeezed, 
and out shoot two jets of sea- water into the face of the 
observer. 
The creature, not inaptly termed a sea-squirt,” is an Asci- 
dian ; * belonging to a class called Molluscoida, from a zoologi- 
cal, rather than an external and obvious, resemblance to the 
Mollusca — e.g., limpets, whelks, razor-shells, mussels, oysters, 
cuttle-fish, sea-hares. 
Tlie Tiinicata, or Ascidioida — that division of the Mollus- 
coida with wliich we are at present concerned — comprise, 
besides the sedentary “ sea-scpiirt,” some roving oceanic members 
[PLATF XLYH.] 
• Derived from the Greek amcn^, a wine-skin (the leather-bottel ” of 
the Orientals), to which the animal in question bears no slight resemblance. 
