OP NORTHUMBEELAND AND DURHAM. 113 



The smaller size more varied markings, and shorter and more 

 rounded convolutions, distinguish this species from the last. — 

 The wheel-like markings ally it to the B. rotifera of Milne-Ed- 

 wards, but the colour never approaches to red, and the folds of 

 B. rotifera appear more elongated than in ours. In this respect 

 our species approaches more nearly to the arrangement of B. 

 albicans. 



3. B. ALBICANS, M. Edw. 



Botrylloides alhicans,'F orh. and Hani. Brit. Moll. i. 24, t. A, 

 f. 8. 

 On the under side of stones between tide-marks, St. Mary's 

 Island. — A. H. 



4. B. RAMULOSA, Aid. and Hanc. 



General envelope colourless, pellucid, with a few pale yellow 

 spots on the margin. Systems of individuals winding, much in- 

 volved ; and having a broad cream-coloured belt down the cen- 

 tre, following the sinuations. Animals of an obscure brownish 

 yellow, with the lower half pale opake yellow. 



On the under side of stones in pools between tide-marks at 

 Cullercoats, rare. — A. H. 



This species, which is in patches of upwards of an inch and a 

 quarter across, is at once distinguished from B. Leachii by the 

 opake belt of cream-colour that passes along the centre of the 

 various systems of animals. 



The above attempt to describe the Tunicata of our coast, im- 

 perfect as it is, may serve as a ground-work for future investiga- 

 tions. Some other forms are known to us which we have 

 not ventured to describe, though we have seen sufficient 

 to convince us that many species yet remain to reward the la- 

 bours of future enquirers. The compound species are extremely 

 difficult to make out, both on account of their great similarity, 

 and because the same species, and even the same individual, is 

 very apt to vary under different circumstances. 



