DAVIDSON 
— SCOTTISH CARBONIFEROUS BRACIIIOPODA. 
183 
pansious arc wide, flattened, aivl clearly rlcfiiicd. The whole surface is covered 
with numerous soiuewimt irregular transverse undulated wrinkles, while 
numerous elongated ])ustules or tubercles are closely scattered over the entire 
surface, and from wiiich projected small adpressed tubular spines. The dorsal 
valve is but slightly concave, with a small uiesial elevation or fold ; it is like- 
wise ornamented witli numerous transverse wrinkles and elongated pits in lieu 
of tlic tubercles observable in the opposite one. 
No Scottish interiors of this shell have been hitherto discovered ; but Eng- 
lish specimens show that the muscular and other hn])ressious did not differ 
materially in detail from those of P. scahriculus and of others described iu this 
monograph. P. pmtnlosiis sometimes attained large proportions ; but the only 
Scottish example I was able to examine did not exceed some eleven lines and 
a-half in length by foui'teen in width. 
In Haddingtonshire it is stated to occur at Cat Craig, near Dunbar ; and 
another example, labelled from the north of Glasgow,* is preserved in the 
Museum of Practical Geology. In Stirliugsliire a specimen was found in shale, 
under the Campsie main limestone by Mr. G. Somervile. 
Tlie sixteen species of Productus described as having been found in Scotland 
form part of Prof, de Kouiuck's following groups : — 
C Productus giganteus, Martin sp. 
Steiati \ lat'mimns, J. Sowerby. 
(, — — cora, d'Orbigny. 
Undati /oidatus, Defrance. 
semireticidatus, Martin sp. 
Var. Martini, Sowerby. 
cmtatus, J. Sowerby. 
Youngiamts, Davidson. 
longispinns, J. Sowerby. 
cartmiurius, de Koninck. 
spinulosus, Sowerby. 
Semireticulati 
Spinosi < scahriculus, Martin sp. 
(. pusfulosus, Phillips. 
Pimbriati \ pundatus, Martin sn. 
(. junbriatus, J. Sowerby. 
Caperati aculeatm, Martin sp. 
Mesolobi mesolohus, Phillips. 
It is probable that in time better and more abundant materials relative to 
some few of the species will be discovered, and wliich will enable palaeon- 
tologists to determine more exactly whether one or two of those above 
enumerated might not be mere varieties of some already recorded species ; and 
again whether we are justified or otherwise while considering P. Martini as a 
simple variation in shape of P. semireticulatus.^ Interiors of P. undatus. 
* The exact Scottish locality from whence this specimen, P. carbonaritis, and Sp. pinguis 
were obtained appears to be unknown. These specimens, which have all the appearance of 
Scottish sheUs, are labelled "north of Glasgow" in the Museiim of Practical Geology, but 
were in all probability derived from some other portion of the country, for otlienvise it would 
be strange that no examples of the two last have been met with by any of the collectors who 
have exijiored with much care the numerous locaUties to the north of Glasgow. 
t Mr. G. Tate, as well as some other palasontologists, seem desirous of retaining P. semi- 
reticulntus and F. Murtiiii as separate species ; and Prof, de Koninck infonns me that he now 
feels uncertain whether the two should be considered as distinct. These shells have been 
described separately in this monograph, as vai'. semircticiilafns and var. Martini ; and may 
therefore be retained as specific denominations by those who might consider such a tiring 
desirable. 
