the TronJItjem Fiord, 117 



Section I. Adherent varieties. 



Var. 1. (hntata, Ell. *S: Sol. (PI. VI. fig. 1). — Zocecium more 

 or less produced and punctate ; margin of area crowned with 

 .'<pine.'5, variable in number, usually from four to ten, rarely 

 twelve, and one at the base larger and stronger than the rest, 

 but, like them, calcareous. Very common in the British Isles, 

 incrusting shells, stones, and weeds. (Busk, Brit. Mus. Cat. 

 Cheilostomata, pt. ii. pi. Ixxi. fig. 1 ; Hincks, Brit. Mar. Pol. 

 pi. xxiii. figs. 2, 3.) 



Var. 2. tenuis, Norman (Pi. VI. fig. 2). — This form corre- 

 sponds in all respects with the last, except that it is more 

 delicate in structure, the spines more slender, and the basal 

 spine reduced in size, so as to be no larger than the others. 



An extreme form of var. tenuis in my collection (formerly 

 in Barlee's), incrusting a Mytilus, has the greater portion of 

 the zooeeia wholly devoid of spines or set£e ; other zooecia 

 have two or three little denticles (rather than spines) ; others 

 resemble Hincks's pi. xxiii. fig. 4; while some few show the 

 passage to the usual state of var. tenuis. 



Forma stellata, Thompson. — This is either of the foregoing 

 varieties living on the inside of bivalves or on broad-leaved 

 seaweeds, and the zoarium growing out into digitate exten- 

 sions at the margins, so that its form is more or less stellate. 



Var. 8. Ujinca^ Norman, = var. Lceflingiana^ Moll (PL VI. 

 figs. 8-5). — I have never seen this variety incrusting stones 

 or shells, but always seaweeds. The zooecia have the margins 

 much stronger than in the preceding varieties ; the posterior 

 punctate portion is often reduced to a minimum, especially in 

 the central portions of the zoarium, where the punctated struc- 

 ture is wholly absent or can only be seen at the base of the 

 posterior spine. The lateral spines are usually six, stout and 

 strong ; the posterior central spine is greatly developed, some- 

 times still preserving its spine-like character, at another trans- 

 formed into a great chitinous seta, which is two, three, or even 

 four times the length of the zocecium : when incrusting a flat 

 weed these long seta3 are developed most freely at the margins ; 

 when investing small roinid weeds the whole zoarium elegantly 

 bristles with them, and sometimes two, three, or four spines 

 are changed into the great setse. (Blainville, Man. d'Actinol. 

 pi. Ixxv. fig. 2 ; Hincks, pi. xxiii. fig. 1.) 



Var. 4. Reaumurianay Moll, = Electra verticillata, Lamx. 



