Marine Fauna and Fishes of St. Andrews. 145 



section of our British HalichondricB is with H. regidaris. The 

 spicula of the two species are as nearly alike in size and pro- 

 portions as possible ; but this is their only approximation to 

 each other. In their other characters they differ to a con- 

 siderable extent. The colour of H. regularis in the dried 

 state is milk-white ; that of i7! M'ltitoshii is nut-brown. An- 

 other important difference is, that while the skeleton of H. 

 regidaris is remarkable for its symmetry, that of ff. M'Intoshit 

 is irregular to a very considerable degree." 



This form is not uncommon on the under surface of stones 

 in tide-runs and somewhat muddy pools not far from high- 

 water mark at the East Rocks. Its greyish brown colour, 

 smooth surface, and prominent, well-defined oscula distinguish 

 it at first sight from its allies. 



Halickondria incrustans, Esper ; Bowerb. vol. ii. p. 249. 



Occasionally found under stones near low-water mark, 

 especially at the East Rocks. It forms a thickish crust ; and 

 the spicula very much resemble one of the knobbed walking- 

 sticks which taper from above dowuAvards. 



Suborder III. Keratosa. 



Chalina oculata^ Pallas ; Bowerb. vol. ii. p. 361. 



Thrown in great profusion on the West Sands after storms ; 

 and small specimens are also found under the ledges of rocks 

 near low-water mark. The shape of the specimens varies 

 much : some are flattened and much divided into branches of 

 various sizes, either naiTow or broad ; others have their 

 branches much matted together so as to form a connected and 

 somewhat coarse "gorgonian" appearance, more or less sepa- 

 rated at the tip. In some the branches arise mostly fi-om one 

 side of an unbroken prolongation of the sponge-tissue. One 

 grows on a valve of Mytilus modiolus^ and has a mass of 

 Ilalichondria jpanicea round a branch at its base. Another 

 envelops the stem and branches of Delesseria sanguinea^ the 

 leaves of which appear here and there from the centre of 

 the sponge. Many are attached to small rolled stones. 

 Those from the beach are loaded with sand, spines of the 

 common and purple heart urchins, bristles of the sea-mouse ;' 

 and many starfishes seek refuge in their interstices. 



Chalina limhata^ Bowerb. ; vol. ii. p. 373. 

 Not uncommon on the under surfaces of stones in tidal })Ools, 

 either coating the surface of the stone or attached to the stems 

 of Corallina officinalis. 



[To be continued.] 



