174 The American Geologist. September, 1895- 
pygidium ; eyes nearly transverse to the axis, very large and 
prominent, situated on the anterior margin, separated only by 
the axis. The specimen represented in figure 6 is in the para- 
protaspis stage, and measures .96 mm. in length. It shows 
an advance over the other in its size, its larger pygidium with 
grooved pleura, and the beginning of the recession of the eyes. 
The adult of this small species is shown in outline enlarged 
two diameters, in figure 7. The principal changes from the 
larva which should be noticed are: the loss of the four ante- 
rior annulations of the glabella, the neck segment being the 
only one wholly defined, although the basal lobes represent 
remnants of the next anterior ; the translation of the eyes 
backward as far as the pleura of the neck segment, and the 
change from a transverse to a parallel position with respect 
to the axis. 
In the original description of this species,-** no mention was 
made of fine undulating striai ornamenting the entire dorsal 
surface of the test, nor of the basal lobes of the glabella. Both 
these features are present in the type specimen, which is from 
Cincinnati, Ohio, as well as in all the specimens from the 
Utica slate, near Rome, New York. With these additional 
characters, the species is very closely related to Pvo'ctus 
decorus Barrande. 
Dalmajiite.s socialis Barrande; plate IX, figures 8-11; from 
the Ordovician of Bohemia; after Barrande.-^ A nearly com- 
plete series of the growth stages of this species is given by 
Barrande. The earliest, or anaprotaspis, stage found (figure 
8) exhibits an outline and axis similar to Artdatipifi. The 
eyes are quite large and situated, as in the same stage of 
Pro'etKs, transverse to the axis, on the anterior border. Genal 
angles present, but in this case not produced by the free- 
cheeks as in 8(1 <> and Ptiichoparia; glabella strongly annulated,. 
increasing in diameter anteriorly, although not exi)anding at 
the frontal margin as in Sao, etc. In the two following stages 
(figures 9, 10), the pygidium increases in size, and the pleura 
are defined. To reach maturity (figure 11), eleven segments 
are developed in the thorax, the glabella becomes more promi- 
nently developed in front, but the five annulations are main- 
tained. The eyes have travelletl in and back as far as the 
third head segment, and their longer axes have swung around 
