CATALOGUE OF TUNICATA, 99 



Goodsiria lapidosa, Herdm., :;; PL Pst. III., figs. 112. 



External appearance. The colony is a solid cake-like mass (fig. 2), 

 in which the Ascidiozooids are closely placed and completely imbedded. 

 There are distinct upper and lower surfaces, and the Ascidiozooids form 

 a single layer, being placed side by side with their antero-posterior 

 axes vertical, and their branchial apertures all on the same surface 

 (fig. 1). The whole of the colony, both upper and lower surfaces, is 

 closely encrusted with sand grains and shell fragments. The colour is 

 a stone grey, slightly darker in places. 



The test is firm and cartilaginous, and is stiffened on the surface by 

 the imbedded sand. The colour in the interior is a light grey. Vessels 

 are present, but they are few in number and very small. There are no 

 bladder cells, and the ordinary test cells are small (fig. 3). The Ascidio- 

 zooids are so large that there is comparatively little test present in the 

 colony, only from 1 mm. to O5 mm. between each pair (see fig. 1). 



The Ascidiozooids are about 1-5 cm. in length and O4 cm. in breadth. 

 They are not divided into thorax and abdomen. The apertures are 

 distinctly 4-lobed. 



The mantle is very delicate and thin over the branchial sac. Both 

 longitudinal and transverse muscles are present (fig. 5), but they are 

 arranged irregularly. 



The Branchial sac is large and well developed. There are 4 branchial 

 folds on each side between the endostyle and the dorsal lamina, but the 

 first or dorsalmost of these is rudimentary, and consists only of 3 or 4 

 internal longitudinal bars placed close together without forming a pro- 

 jection. The rest have generally about 9 bars each, and form well- 

 marked projections (see figs. 6 and 7). In the interspace between each 

 pair of folds there are 2 internal longitudinal bars, but between the 

 dorsal lamina and the rudimentary fold there is only 1 such bar. The 

 transverse vessels are wide. There are from 3 to 5 (generally 3) 

 stigmata in a mesh, except in the series next the endostyle where there 

 are 6 or 7. The stigmata are short and wide and very irregular, being in 

 different positions and set at different angles. Sometimes 2 small ones, 

 one above the other, take the place of one ordinary one ; sometimes 1 

 large one is found instead of 2 or 3 of the usual size. Now and then 

 one of the stigmata lies alongside a transverse vessel, and occasionally a 

 transverse vessel splits into two and then unites again, leaving an 

 elongated space between. 



The dorsal lamina is a very narrow, plain membrane. 



"Revision," p. 637. 



