CATALOGUE OF TUNICATA. 73 



Amaroucium protectans, n. sp., PL Pel. III., figs. 7 10. 



External appearance. The colony is thick, massive, dome-like, and 

 not stalked. On its lower surface it is concave where it is slightly 

 attached to the dorsal surface of the crab Dromia excavata, Haswell 

 (PL Pel. III., fig. 7). The upper surface is strongly convex, and has the 

 Ascidiozooids scattered all over it. The colour is a dull yellowish grey, 

 in some cases being darker towards the lower part of the colony from 

 the presence of imbedded sand grains. The average dimensions of two 

 shapes of colony are as follows : 



A. B. 



Length (height)... ... -4-5 cm. ... 5'5 cm. 



Breadth 1OO cm. ... 7'5 cm. 



Thickness 7'5 cm. ... 6'5 cm. 



The Ascidiozooids are about 1 cm. to T5 cm. in length and T5 mm. in 

 breadth. They lie in the test at right angles to the surface. The body 

 is divided into thorax, abdomen, and a short post-abdomen (PL Pel. III., 

 fig. 8) terminating in a vascular appendage, which, in some cases, is long, 

 branched, and budding. 



The test has many bladder cells, but 110 pigment cells. The small 

 test cells are chiefly spherical, and are not very numerous. 



The mantle has strong longitudinally-running muscle fibres over the 

 post-abdomen, and both longitudinal and transverse fibres are present in 

 the mantle over the branchial sac, the transverse bundles being very 

 closely placed. Sometimes the mantle over the branchial sac is marked 

 with black pigment spots. 



The branchial sac has about 10 rows of long, narrow stigmata (PI. 

 Pel. III., fig. 10). The transverse vessels bear large horizontal mem- 

 branes. There are usually a series of tailed larvae placed in a single row 

 along the thorax. 



The dorsal lamina is represented by a series of rather long languets, 

 set about their own length apart, opposite the transverse vessels (PL 

 Pel. III., fig. 9). 



The tentacles are 24 in number and of three sizes, 6 large, 6 medium, 

 and 12 very much smaller, which arise on a level anterior to the others. 



Alimentary canal. The oesophagus is long and has its wall thrown 

 into transverse folds ; and before entering the stomach it narrows con- 

 siderably. The stomach is globular or oval, and has its wall longi- 

 tudinally grooved (PL Pel. III., fig. 8). The intestine is narrow on first 

 leaving the stomach, and runs for a short distance posteriorly, and then 

 becomes rapidly wider and thin-walled, and runs anteriorly alongside the 



