BRACHIOPODA. 
325 
Shell substance fibrous, strongly punctate. 
Type, Productus Martini, Sowerby, = Anomites productus, Martin, == Anomites 
semireticulatus, Martin, = Productus semireticulatus, Martin. Lower Carboniferous 
limestone to Coal Measures. 
Observations. It is the usage of some systematists to regard the genus 
Productus as a starting point in the classification of the articulate brachiopoda 
on account of the usual absence of the cardinal area and teeth. These are 
features which are unquestionably in an obsolescent condition. It is rarely, 
however, that some trace of them is not discernible, and it has been observed 
by various writers, that they are sometimes well-defined, and that too in species 
where they are normally wanting. For example, they may be present 
in the species Productus semireticulatus and P. Nebrascensis. In these features 
Productus is degenerate, but this degeneracy has apparently not extended to 
other points of structure, and the genus certainly lacks the simplicity of plan 
in its structure so apparent in Orthis. Its late appearance in the Palaeozoic 
and its close kinship to the CHONETES-stock is evidence of its derivation from 
that source. The earliest phase of the productoid type, which is abundantly 
developed in the Devonian, and which has been distinguished by the name of 
Productella, retains the articulating processes and cardinal area with persist¬ 
ence throughout the period immediately preceding the appearance of normal 
Productus. These features are, however, always more or less obscure, and 
manifestly approaching desuetude. Leaving for the present the consideration 
of this and the other generic or subgeneric divisions, which have been taken 
from Productus, we have, in this genus, to deal with a very homogeneous 
group of fossils. 
A grouping of the species of Productus was proposed by de Yerneuil in 
1845,* and this was amended and somewhat amplified by de Koninck in 1847.f 
Dr. Waagen, in his magnificent treatise on the Producti of the Salt-Range, 
is the latest writer who has discussed the genus at length, and has adopted 
this classification with some modifications and additions; it is evident that no 
* Geologie de la Russie, p. 253. 
f Monographic du genre Productus, p. 29. 
