BRACHIOPODA. 
219 
group are actually punctate. It is not surprising to find some primordial 
species of Orthis, for example 0. Billingsi (Protorthis), affording indications of 
a punctated shell, which, with other characters, may be interpreted as showing 
relationship to Clttamconites and the streptorhynchoids in which a punctate 
structure is never wanting. 
It should not be forgotten that a grouping of the species of Orthis was made 
by de Verneuil in 1845,* and by Quenstedt in 1871.f The very broad concep¬ 
tion of generic values which generally prevailed at the date of the former work, 
but which at the latter period were maintained by few students, renders these 
groupings of little value in the present state of our knowledge. In de Ver- 
neuil’s classification, based upon thirty-five species and varieties of “ Orthis,” 
were two groups of the first order, A, Sinuata, corresponding to King’s Schizo- 
phoria, and B, non-Sinuata. The latter was divided into a 1 , striata, b 1 , plicosa. 
The striata were again divided, a 3 , arcuostriata, in which the delthyrium is open, 
and b 2 , redostriata, in which the delthyrium is closed. The former of these 
included the a 3 , uniarea, with a rudimentary area on the brachial valve (ex. 
0. elegans, Bouchard), and b 3 , biarea, with areas developed on both valves. Of 
the biarea were two subdivisions, a 4 , Jiliarea (ex. 0. Michelini = Rhipido- 
mella ; 0. tetragona = Schizophoria) ; b 4 , elegantula (ex. O. elegantula, 0. parva 
= Dalmanella). Of b’, redostriata, were also the subdivisions a 3 , uniarea, and b 3 , 
biarea, and of the former of these two groups a 4 , with three or more secondary 
striae in the furrows (= Orthothetes) ; b 1 , with but-one or two such striae 
(=Meekella, Streptorhynchus, Derbya, Orthothetes); of the latter, biarea, 
were a 4 , Gonambonites (= Clitambonites), and b 4 , Pronites (= Clitambonites 
and Orthisina). The b 1 , plicosa, were divided into those with simple plications 
(0. calligramma), and those with dichotomous plications (0. extensa, Pander). 
Quenstedt instituted three principal divisions of his orthidae : (1) ventriplexa, 
with convex pedicle-valve; (2) ventricava or expansa, with concave pedicle-valve; 
(3) dorsicava, with concave brachial valve. Representatives of the first in¬ 
clude Schizophoria, Porambonites, Orthisina, Clitambonites, Streptorhynchus, 
* Geol. Russ, et- des inont. de PUi-al. 
t Petrefactenkunde Deutschlands: Brachiopoden. 
