76 ASCIDIANS CHAP. 
“Challenger” expedition; eight or nine species are now known 
from various parts of the world, ranging in depth from 630 to 
2425 fathoms. Most of the species are from the Pacific; only 
one from the North Atlantic. The curiously curved type of 
spicule found in the branchial sac and other organs is shown at 
Fig. 50, C (p. 87). 
Amongst the Cynthiidae are found most varied conditions of 
the reproductive organs. The gonads are sometimes on both, some- 
times on only one side of the body, sometimes in one or several 
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Ny 
MY 
Fic. 39.—Various Cynthiidae. A, two forms of Styelopsis grossularia, Van Ben. ; B. 
Forbesella tessellata, Forb.; C, Polycarpa aurata, Q. and G.; D, Styela clava, 
Herdman; E, Polycarpa tinctor, Q. and G.; F, Cynthia formosa, Herdman ; G, 
Polycarpa comata, Alder ; H, Polycarpa pedata, Herdman ; I, Pelonaia corrugata, 
Forb. and Goods. (After Herdman.) 
branched masses, and sometimes distributed as a large number 
of minute “polycarps” over the inner surface of the mantle. 
The family Cynthiidae is the largest section of the Simple 
Ascidians. The species range from the size of a pea to that of a 
large cocoa-nut. They are for the most part opaque, and often 
richly coloured—treds, yellows and rich browns predominating— 
and so look very different to the grey gelatinous Ascidiidae, and to 
the sand-encrusted Molgulidae. They extend from between tide- 
marks (Styelopsis grossularia), down to the abysses (Styela bythia 
and S. sgwamosa at 2600 fathoms). Some genera (Styela and the 
closely related Dendrodoa), extend far into Arctic seas, but many 
allied forms (Styela and Polycarpa) are also found in the tropics. 
