CATALOGUE OF TUNICATA. 95 



f Colony discoid, branchial sac folded ... G. placenta, Herdm. 



10 -! Colony not discoid, branchial sac not 



I folded 11 



/ Colony elongated or irregular, not pedun- 



11 -j culated G. coccinea, Gun. 



( Colony round or pyriform, pedunculated G. pedunculata, Herdm. 



Chorizocormus sydneyensis, Herdm.,* PI. Pst. I., figs. 1 7. 



External appearance. The colony consists of a number of small 

 masses of test, in each of which one or several Ascidiozooids are im- 

 bedded, and which are united into straggling groups by thin extensions 

 of the test, which may be called stolons (fig. 1). The whole is attached 

 to and partly encrusts some slender algae, with which it forms an 

 irregular network. The stolons are light grey and rather transparent, 

 but in the more massive parts of the colony the closely-placed Ascidio- 

 zooids give rise to a dark purplish brown colour. 



The test is cartilaginous. It contains many vessels, which branch 

 freely (fig. 2), and have terminal knobs of rounded and ovate forms 

 filled with dark blood corpuscles. There are no bladder cells and no 

 pigment cells. The ordinary test cells are very small. 



The Ascidiozooids are about 4 mm. in length, and the same in breadth. 

 The viscera lie on the left side of the branchial sac (fig. 5), so no separate 

 abdomen is present. 



The mantle has both a transverse and a longitudinal musculature. The 

 muscle bands are rather irregularly arranged. 



The branchial sac has internal longitudinal bars, but no folds. There 

 are 8 rows of stigmata, and from 4 to 6 stigmata in a mesh (fig. 3). The 

 stigmata are about six or seven times as long as wide. 



The dorsal lamina is a plain, straight membrane. 



The tentacles are rather short and thick. They are about 16 to 20 in 

 number, and are of two sizes. There are from 5 to 7 large ones, with 

 from 1 to 3 smaller ones between each pair of larger. There is con- 

 siderable variability both in the number and the size of the smaller 

 tentacles. At the base of the atrial siphon there are about 25 very small 

 and slender atrial tentacles. 



The dorsal tubercle has a simple circular opening (fig. 4). 



The alimentary canal lies 011 the left side of the branchial sac. Its 

 course is at first posteriorly and ventrally, then anteriorly, then dorsally 

 and posteriorly, then dorsally and anteriorly. The directions are similar 



* "Revision," p. 636. 



