NORTHUMBERLAND AND DURHAM. 153 



confirmed me in tlie belief that tliey are really distinct species. 

 Tlie best character is found in tlie aviciilarimn, " the form and 

 position of wliicli," Mr. Busk remarks, "afford apparently an 

 invariable character, readily discernible, and sufficient as a 

 specific distinction."* The avicularium of S. fdrciiniaoides is 

 semicircular and arched upwards; that of >?. sijiuosaia triangular, 

 pointing downwards, and always sloj)ing a little to one side. 

 In addition to this, the form of the under lip of the cell differs 

 in the two species: in S. farcimniokles it is slightly arched in 

 the centre; in S. shmosa it is quite straight, and rather pro- 

 jecting, with a sinus at each end. Tlie form of the cells, though 

 variable, is more inclined to the rhomboidal or lozenge shajjc in 

 S. farciminoides, and to the hexagonal or octagonal in S. sinuosa. 

 The arched top is found in young specimens of both. Upon the 

 whole I think there cannot be a doubt of the distinctness of the 

 two species, and I am glad to find that Professor Busk now 

 coincides with me in this opinion. 



Sub-order. CTENOSTOMATA, BusIc. 

 Family. ALCYONIDIAD^E, Johnston. 



44. ALCYONIDIUM, Lamouroux. 



1. A. GELATINOSUM, Linil. 



Johns. Brit. Zooph., 358, t. Ixviii., f. 1 — 3. 

 Attached to old shells and stones in the Laminarian and 

 Coralline zones; frequent. On the sides of rocks at 

 low-water mark, Bamborough. 



2. A. HiRSUTUM, Flem. 



Johns. Brit. Zooph., 3G0, t. IxLx., f. 1, 2. 

 On Corallina officinalis and other sea-weeds between tide- 

 marks and in shallow water; common. 

 At Cullercoats and on the adjacent coast, this species is of 

 very humble growth, seldom exceeding one or two inches in 

 height, and very slightly lobed — often, indeed, a mere crust, 

 not rising into a free state; but in the north of Northum- 

 berland it reaches a much larger size, and becomes much lobed 



* Catal. Mar. Pol., p IC. 



