ASCIDIA. Sl 
our typical form Ascidia, of which there are many species 
in British seas, widely distributed round our coasts. Two 
other common British forms, belonging to this family, are 
Ciona intestinalis, with a very soft, pale-green test and 
languets in place of a dorsal lamina, and Corella parallelo- 
gramma, in which the stigmata of the branchial sac are 
curved to form beautiful spirals. 
Family II. Cynramp# :— Solitary fixed Ascidians, 
usually with leathery test; branchial and atrial apertures 
both 4-lobed. Branchial sac longitudinally folded; stig- 
mata straight; tentacles simple or compound. 
This is the largest family of Simple Ascidians, and 
contains a number of genera, about six of which are 
British. Styela has simple tentacles, and not more than 
4-folds on each side of the branchial sac. A very common 
species all round our coasts, between tide marks, is the 
little red Styela (or Styelopsis) grossularia. In Cynthia 
the tentacles are compound, and there are more than 
4 folds, usually 7 or 8, on each side of the branchial sac. 
The curious little Forbesella tessellata, from deep water 
in the Irish Sea, is in some respects intermediate between 
Styela and Cynthia. 
Family IV. Moneunip# :— Solitary Ascidians, often 
not fixed; branchial aperture 6-lobed, atrial 4-lobed. Test 
usually encrusted with sand. Branchial sac longitudinally 
folded; stigmata more or less curved, usually arranged in 
spirals; tentacles compound. 
Several species of Molgula, all looking when dredged 
like little sandy balls, and one of Hugyra (E. glutinans), 
are common at a few fathoms depth round most parts of 
our coasts. 
