CARBONIFEROUS BRACHIOPODA. 
295 
Pamily— PR0DUCTIDJ5:., Gray. 
Genus Producttjs, Sowerhy. 
Intimate Shell-structure. — Until 1879 nothing but indefinite statements had been 
made with respect to the shell-striictuve of the Pkoductid/e. In 1847, in vol. iv, p. 67, 
of the ' Quarterly Journal of the Geological Society,' Mr. 13. Sharpe observed, "Among 
the ProducfcB and some species of Chonetes, the punctations are closed up everywhere, 
except at the edge, by a gradual deposit of shelly matter in the interior." In 1853, in 
his chapter on the intimate structure of the shells of Brachiopoda, p. 36 and 37 of my 
General Introduction, Dr. Carpentei* says : " Family PRODUCTiDiE. — In all the genera 
of this family large perforations exist, resembling those of Strojjhomena dej^ressa in their 
general aspect, and in the infundibular arrangement of the laminse of the shell around 
them. Productus. — Of this genus I have examined the following species : Cora, 
Fleminyii, horridus, and striatas, all of which have well-marked perforations ;" and he 
adds that Strophalosia and Chonetes are both perforated like Productus. Dr. Carpenter 
does not, however, clearly explain the nature of the perforations to which he alludes, or 
say whether or not they traverse the entire thickness of shell ; he adds, " I am disposed 
to think, however, that in some of the massive shells of this group, which appear to have 
been formed by the addition of successive laminae to the interior, the internal laminae 
were sometimes destitute of perforations — at least at a distance from the margin — as 
stated by Mr. D. Sharpe." 
On the 11th of February, 1879, Prof. L. de Koninck writes me, " J^ai regiu un grand 
envoi de fossiles d'Amerique. Parmi ces fossiles j'ai trouve un specimen de Productus 
semireticidaius, dont le test est perfore sur plus de la moitie de son etendue, et crible de 
petites perforations serrees que Pon dirait produites par des picures d'epingles. Vous 
voyez done que le caractere d'avoir le tet perfore ne suffit pas pour etabli un genre et 
que mon idee que les tets de la plupart des Brachiopodes ont ete perfores commence a se 
justifier." 
I at once wrote to Prof, de Koninck, and obtained from him the kind loan of the 
Productus which he states to be perforated. On its arrival at my house I soon perceived 
that on the well-preserved outer surface of the shell no perforations were visible, and that 
it was only on the decorticated parts that perforations were clearly observable. I soon 
after forwarded the specimen to Prof. King for his valuable opinion, and informed Mr. 
John Young, of the Hunteriau Museum, Glasgow, of Prof, de Koninck's statement. 
This led Mr, Young to devote considerable time to the careful investigation of the shell 
structure of this genus, and he has kindly communicated to me the result of his examina- 
