Dr. W. C. M'Intosh on the Zoojyhjtes of St. Andrews. 207 



pools near low-water mark, as Avell as coating the stems of 

 Laminarue with a hairy fringe fully half an inch in height. 

 In a fine example of the latter many of the stems possess one 

 or two branches, and the gonothecse here and there have a 

 stalk composed of several rings. 



Genus Obelia, P^ron & Lesueur. 

 Ohelia geniculata, L. ; Hincks, Brit. H. Z. vol. i. p. 149. 



Common on laminarian blades thrown on the West Sands 

 after storms, forming a miniature cover amidst which many 

 Nudibranchs find food and shelter. It occurs plentifully also 

 on Halidrys siliquosa and other seaweeds near low-water 

 mark, and on crabs. In the interior of many of the gonothecse 

 are the young of a Pycnogonidian. 



Ohelia longissima^ Pallas ; Hincks, Brit. H. Z. vol. i. p. 154. 



Abundant in deep water. It bristles on every branch or 

 fragment of wood which has been submerged for some weeks. 

 It appears also in a very interesting condition in the peculiar 

 rounded balls formed by the rolling action of the waves on 

 the beach ; these zoophytic masses are either spherical or 

 rounded-oblong, and the fibres are firmly felted together *. In 

 this state the present species is stripped of its minute branches, 

 and feels bristly and crisp. The same rolled masses (also 

 chiefly composed of an Ohelia allied to the present form) were 

 brought from the shore of a New-Zealand bay by Dr. Lauder 

 Lindsay, who kindly sent them to me. They are formed in a 

 similar manner as the well-known balls in Loch Tay, where 

 the rolling action of the waves produces perfectly round masses, 

 often as large as a spherical sliot of thirty or forty pounds, com- 

 posed of the linear leaves of the larches and pines which shade 

 its margin. Miss M'Leod, of Paible, brought me spherical 

 masses of a similar description from a fi-eshwater lake in 

 South Uist, the species in this case, according to Prof. Dickie, 

 being CladopJiora gJomerata. 0. longissima affords a favourite 

 site for young mussels. 



Ohelia dicliotoma^ L. ; Hincks, Brit. H. Z. vol. i. p. 156. 



Not common ; parasitical upon a piece of seaweed from the 

 laminarian region, and reaching about 3 inches high. 



* One of these masses so closelv resembled the chignon lately in vogue 

 that it was secretly used by a patient for this purpose, and I learned that 

 it was only the disagreeable abundance of sand in its tissue that saved it 

 from further duty in this respect. 



15* 



