T. Davidson — Tertiary Brachiopoda. 359 



vary from l-20tli to nearly l-12th of an inch in breadth., and fre- 

 quently attain a length of several inches. The hydrothec^ have a 

 straight, or but slightly convex outer margin, which is parallel with 

 the general outline of the polypary ; and are produced distally, until 

 forming an angle of about 45 degrees with the axis. In well pre- 

 served specimens a few of the hydrothecee near the proximal end of 

 the polypary have a slender acutely pointed spine proceeding from 

 their outer margin, and directed more or less towards the distal end 

 of the polypary ; and in the branches, minute pustules, marking the 

 junction of the hydrothecse and periderm, are sometimes, though 

 rarely, observed. The enlarged drawings of portions of the branches 

 of this species are taken from the complete specimen figured, and 

 present a variety of form difficult to comprehend. Indeed, I think 

 it will be better to offer no explanation of the appearances here seen 

 until better preserved specimens than any I am acquainted with can 

 be examined. Emmons' species are evidently founded on imper- 

 fectly and unequally preserved specimens of JD. ramosus. 



Log. Arenig: — Ty-obry, near Portmadoc, North Wales (Salter). 

 Llandeilo : — Builth, and Abereidy Bay, Wales. Dobb's Linn, Hartfell, 

 Glenkiln Burn, Wanlockhead, etc., near Moffat, Dumfriesshire. Loch 

 Eyan, Wigtownshire. Caradoc : — Canada and New York (Hudson 

 Eiver Group.) Also recorded by Professor McCoy, from the Coniston 

 Flags, near Ulverston, and from the Lower Silurian rocks of Mel- 

 bourne, etc., Australia ; and by Dr. Emmons {inequalis) from 

 Tennessee. 



EXPLANATION OF PLATE XVI. 



Fig. 1. Dicranograptus sextans, Hall. \a. A specimen natural size. 15. The same 

 magnified 5 diameters (restored). Ic. The proximal end of another 

 specimen slightly enlarged (from a drawing hy Dr. H. A. Nicholson). 



Fig. 2. Dicranograptus formosus, Hopk. 2a. A specimen nat. size. 2b. and c. 

 Portions of different specimens mag. 5 dia. 2d. A piece of shale (from 

 the Beld Craig Burn) covered with impressions. 



Fig. 3. Dicranograptus Nicholsoni, Hopk. 3a. A specimen nat. size. 35. The proxi- 

 mal end of the same mag. 5 dia. 3c. A specimen from the collection of 

 Mr. Carruthers, nat. size. Zd. Part of a branch of the same mag. 5 dia. 



Fig. 4. Dicranograptus Olingani, Carr. 4a. A specimen nat. size. 45. The same 

 mag. 5 dia. 4c. Part of a branch of another specimen, mag. 5 dia. 



Fig. 5. Dicranograptus ramosus, Hall. 5a. A specimen nat. size. 5b, c, and d. 

 Portions of the branches of the same mag. 5 dia. 5e. A portion of 

 another specimen mag. 5 dia. 



III. — On Italian Tertiary Brachiopoda. 



By Thomas Davidson, F.E.S., F.G.S., etc. 



(Plates XVII and XVIII.) 



FOE many years past I have, at intervals, devoted attention to 

 Tertiary Brachiopoda, and I now propose to note down some 

 remarks in connection with those of Italy. 



Of all countries hitherto investigated, Italy has afforded the largest 

 number of species, and of these I have been able to study the best 

 collections, as well as many examples of those which have been 

 found in the South of France, in Spain and in Algeria. The study 



