286 LIVERPOOL MARINE BIOLOGY COMMITTEE REPORT. 



The region at the base of the branchial siphon in this 

 species is shown in Plate VI, fig. 7. The tentacles are of 

 three lengths. There are two of the largest size which are 

 placed laterally, and have masses of pigment cells of a 

 greenish yellow colour at their bases. Those of the next size 

 are also two in number, and are dorsal and ventral in 

 position, while the smallest size consists of a series of four 

 tentacles alternating with the others, but springing from a 

 line placed nearer to the branchial aperture. The dorsal 

 tubercle is small, and is nearly circular in outline (PL VI, 

 fig. 7, d. t.) ; there is no distinct peri-tubercular area. At 

 the ventral edge the peripharyngeal band turns very dis- 

 tinctly posteriorly, to become continuous with the edges of 

 the endostyle (see PI. VI, fig. 7, en.) 



Botryllus violaceus, Milne-Edwards. 



This striking species is fairly common around the south 

 end of the Isle of Man, and it seems to extend further up 

 the shore than any other species of Botryllus, or than any 

 other Compound Ascidians, except perhaps some of the 

 species of Leptoclinum. 



Botryllus violaceus is usually found attached to the under 

 surfaces of large flat stones in tidal pools, and it often forms 

 colonies of very considerable size, several inches in diameter. 

 The colonies are always very thin, and difficult to detach 

 without tearing. The species is very variable in colouring, 

 and Giard * has formed a number of varieties based upon the 

 particular tint of blue and the breadth of the characteristic 

 white lines. Of these the Manx specimens seem to belong 

 to the three varieties, cyanus, scalar and nigricans, and most 

 of them are certainly var. scala, which is, I believe, the 

 commonest British form. 



This species has not previously been recorded from the 

 locality. I have found it before at Lamlash Bay, in the 



* Arch, de Zool. Exper., t. 1, p. 621. 



