REPORT ON THE TUNICATA. 285 



AlgfT in a shore-pool at Port Erin, Isle of Man, on August 

 25th. Unfortunately, Giard, in most of the new species 

 which he formed, described only the external appearance, 

 and especially the colours ; consequently it is almost im- 

 possible to identify spirit specimens from his descriptions; 

 and even in the case of living specimens, on account of the 

 great amount of individual variation found in the Botryllidae 

 it is very desirable to have some anatomical characters to 

 supplement the surface markings. 



This species is in external appearance more like Botryllus 

 moriOf or some of the many allied varieties and species* than 

 any other described form. When living, the colony as a 

 whole was of a dark colour. The test was dull grey, marked 

 with opaque grey or white dots. The Ascidiozooids are not 

 large ; there are from six to twelve in a system, and the 

 systems are not crowded. The colour of the Ascidiozooid 

 was darkish brown, with a lighter streak along the centre, 

 and with distinct white tentacles in the branchial siphon, of 

 which three were more conspicuous than the fourth. The 

 margins of the common cloacal apertures are marked with 

 opaque white lines. 



Botryllus sviaragdm, Milne-Edwards. (PI. VI, fig. 7.) 

 One large and several smaller specimens of this species 

 were found on the shore near Port Erin, during August. 

 Giard f states that the specimens of this species which he 

 examined, had the tentacles yellow, and the ends of the 

 vessels in the test also yellow. In the manx specimens 

 (when alive), the tentacles were white, while the vessels 

 had their terminal bulbs (which were particularly large and 

 conspicuous), of a dark green colour. This species is very 

 variable in its colouring, and several tints of green may 

 even be found in the one colony. 



*See Giard, Archives de Zool. exper., t. 1, p. 629, 1872. 

 fLoc. cit., p. 62G. 



