SMITTIA TRISPINOSA. 355 



The small oval avicularia are equally inconstant, and are 

 often distributed irregularly over the surface of the cells. 

 There is sometimes an amazing profusion of them. 



When very old, the walls of the cells are much thickened, 

 overlaid with a dense crust, and coarsely granulated ; and 

 in this condition some of the familiar features of the spe- 

 cies are almost obliterated. 



HABITAT. On stones, shells, &c., from shallow water to 

 great depths. 



LOCALITIES. One of the commonest of our British spe- 

 cies. Cornwall, 60 fathoms, incrusting Pinna ; S.Devon, 

 very common ; Isle of Man ; Guernsey, in large masses on 

 shell (T. H.) : Hastings (Miss Jelly) : Berwick, deep 

 water (Johnst.) : St. Andrews (Dr. M'Intosh) : Hebrides ; 

 Shetland, 170 fathoms (Norman) : Birterbuy Bay (G. S. 

 Brady) : &c. Var. a. Dogger Bank (T. H.). 



GEOGRAPHICAL DISTRIBUTION. Norway (Lilljeborg) : 

 Bahusia, shells, in great depths (Loven) : Arctic regions, 

 on Rhynchonella (Torell) : Nova Zembla (west), 30-60 

 fathoms ; Kara sea (Stuxberg & Theel) : Gaspe, Gulf of 

 St. Lawrence, about 30 fathoms (Dawson) : Anticosti and 

 Mingan Islands (Packard) : Mazatlan (P. P. Carpenter) : 

 Florida (Pourtales) : Cape Horn, 40 fathoms (Darwin) : 

 Aden (W. Gates) : Adriatic (Grube). Var. a. Green- 

 land, lat. 69 31' N., long. 56 1' W., 100 fathoms (< Va- 

 lorous 'dredgings) : off Frederickshaab, Davis Straits, 100 

 fathoms; Reykjavik Harbour, 15-20 fms. (Wallich). 



RANGE IN TIME. Postpliocene, Canada (Dawson). 



I do not follow Prof. Smitt in substituting Audouiu's 

 specific designation for Johnston's well-known name. Such 

 a course does not seem to be called for by a regard to 

 scientific law, nor would it promote scientific interests. 

 Savigny's figure may possibly be intended as a represen- 



