CRIBRILINID<. 



Colonies forming small (often) circular crusts of a reddish 

 colour. The primary cell appears to be normal, but 

 inferior in size to the rest. 



RANGE OF VARIATION. C. annulata seems to be less varia- 

 ble than any other British species of its genus. The 

 zooecia exhibit slight differences of shape, being sometimes 

 short, ovate, and well rounded off below, and sometimes 

 elongate and produced into a point. The ridges and 

 central keel are more or less pronounced ; and the punc- 

 tures vary in size ; usually they are rather large and trans- 

 versely oval in form. There are commonly three spines, 

 two lateral and one in the centre of the upper margin ; 

 but not unfrequently the latter is replaced by two of 

 smaller size. 



HABITAT. On the fronds of Laminaria and other 

 weeds, on the under surface of stones between tide- 

 marks, and on stones and shells from shallow and deep 

 water. 



LOCALITIES. Shetland, on Laminaria and stones, shal- 

 low water (A. M. N.) : Wick (C. W. P.) : coast of Ayrshire ; 

 Arran ; Cumbraes (Landsborough) : Lamlash, abundant 

 on Laminaria &c ; Oban (T; H.) : St. Andrews (Dr. 

 M'Intosh) : off Sana Island ; Antrim (Hyndman) : Isle 

 of Man, rare; Cornwall (T. H.). 



GEOGRAPHICAL DISTRIBUTION. Eminently a northern 

 form. Greenland (Fabr.)*: Nova Zembla, 4-50 fms. ; 

 Kara Sea (Nordenskiold) : Hammerfast, 40-60 fathoms 

 (Loven) : Spitzbergen, 3-30 fathoms (Smitt) : Bergen, 

 common on Laminaria (M. Sars) : Labrador (A. S. 

 Packard) : Grand Manan, Bay of Fundy, deep water, 

 incrusting shells &c. (Stimpson) : Gulf of St. Lawrence 

 (Dawson) . 



RANGE IN TIME. Scotch Glacial deposits (Geikie). 



* " Habitat in fuels et ul vis minoribus, lepadibua et lapidibus marinia 

 baud infrequens."- -FABR., Fauna Grcenldndica. 



