258 PROCEEDINGS OF THE 



The following are the characters noted : — Main stems and pin- 

 nules strongly carinated ; keel straight ; cells oval, rather more 

 than their length apart ; one at the base of each pinnule and one 

 in the space between ; cells on main stems and pinnules alternate ; 

 pinnules rather more than a line in length, opposite, or slightly 

 sub-alternate ; keel and opening of cell mouths ornamented by a 

 row of small close-set tubercules; other portions of the face strongly 

 granulated between the cells ; reverse face of stem flat or slightly 

 rounded, and ornamented with from three to four rows of granu- 

 lated striae. 



In the number and form of the cells, and in the ornamentation 

 of the stem, this species approaches very closely to our Glauconome 

 Jlexicarinata, of which I think it may be only a straight-keeled 

 variety. The more especially do I think so, as I find that 

 some specimens show a tendency to become slightly flexuous on 

 portions of the stem. As the typical specimens, however, of each 

 variety, should they be considered the same, present very distinct 

 differences, I would suggest that the distinctive names of G. jlexi- 

 carinata and G. recticarinata be retained for these respective forms, 

 in order to mark the distinguishing characters of the keel in each 

 species. 



There remains one other important character to be noted in 

 the form named G. recticarinata. Recently, while examining some 

 fragments of the stem from the shales of Capelrig Quarry, East 

 Kilbride, I found that the cell mouths in one well-preserved speci- 

 men were fringed with a series of delicate hair-like spines or 

 denticles, some fourteen in number, which curved inwards over 

 the opening of the cells, like that seen in some species of recent 

 Flustra. In this character G. recticarinata somewhat resembles 

 our G. stellipora, only in this species the cells are round, and the 

 regular number of spines fringing the cells is eight, and there is 

 a small secondary pore. In the specimen here noted, it appears 

 that the preservation of the hair-like spines is due to their having 

 been crushed down a little way into the hollow of the cell mouths, 

 and thus saved from abrasion. I am inclined to think that the 

 whole celluliferous surface of this species was closely beset with 

 hair-like spines, and that what we now see in the row of tubercules 

 on the keel, and those around the cell mouths, as well as the 

 smaller granulations on other portions of the face, are all due to a 

 series of spines which have been abraded or destroyed, either before 



