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THE VOYAGE OF H.M.S. CHALLENGER. 
Branchial Sac well developed. Eudimentary folds present. Internal longitudinal 
bars strong. 
Dorsal Lamina in tbe form of a plain narrow membrane. 
Tentacles well developed. 
Alimentary Canal not prolonged behind the branchial sac. 
Reproductive Organs in the form of polycarps. 
This genus is founded for a remarkable species, several colonies of which were found 
at Kerguelen Island. It differs from all the other Polystyelidse in producing colonies 
which are not continuous masses or layers of test in which the Ascidiozooids are imbedded, 
but consist of small rounded masses joined irregularly by creeping and sometimes branched 
stolons. This condition suggests at first a similarity to the Clavelinidse amongst Ascidiae 
Simplices, but the structure of the Ascidiozooids shows that if the genus is allied to 
Simple Ascidians it is not through the Clavelinidse but rather through Polycarpa in the 
Cynthiidae. The stolons, like those of the Clavelinidse, consist of test penetrated by 
vascular prolongations from the Ascidiozooids, but that similarity does not, I believe, 
indicate any close or direct relationship. 
In the table given on p. 326 I have placed the present genus in the section of the 
family where the Ascidiozooids are completely imbedded in the common test, but 
occasionally single Ascidiozooids are found isolated, being only connected with the rest of 
the colony by narrow stolons, and in such 'cases they- project considerably above the 
surface. But wherever several Ascidiozooids are placed together in a mass they are 
completely imbedded and do not project. If Chorizocormus had been placed in the first 
section in the table, then it would have been’ readily separated from Thylacium by its 
Ascidiozooids having no abdomen, and from Polystyela by the remarkable shape of the 
colony. The characters will be discussed further under the description of the single 
known species of the genus. 
This form is a valuable link between the other Polystyelidae on the one hand and the 
Cynthiidse amongst Simple Ascidians on the other (see Summary and General Eemarks 
at the end of this Keport). 
Chorizocormus reticulatus, n. sp. (PI. XL VI. figs. 1-8). 
The Colony has the form of a number of more or less rounded masses of small size 
united by irregular creeping stolons, which may branch to form a rude network. The 
surface is moderately smooth, but is slightly incrusted with sand. The colour is light 
grey. 
The size of the species varies greatly. The largest colony is about 15 cm. in 
length, and the smallest is less than 1 cm. 
