ASCIDIANS 



" 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 Oynthiidae 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 



FIG. 39. Various Cyntliiidae. 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, 

 Polyc'irpa 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 reds, 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. squamosa 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. 



