100 G. F. MATTHEW ON ILLUSTRATIONS OF 
Sculpture.—This differs from the last and from P. eteminicus in several respects. The 
band of tubereules on the axial line is not conspicuous, because the whole surface of the 
glabella is more or less granulated, and these granulations merge gradually into the raised 
lines that decorate the front of the glabella. In this variety, too, the raised lines, while they 
are heavier along the front of the glabella than in the two last, do not show conspicuously 
toward the top of the dome, and often are quite absent from the upper half. Another point 
of difference from var. swricoides is the distinct granulations of the whole of the fixed cheek, 
etc., and these granulations differ from those of P. eteminicus in being coarser and thus 
resemble the markings on the surface of P. acadicus of the St. John beds. 
The following are measurements of the heads of this variety :— 
MEASUREMENTS OF THE CEPHALIC SHIELD. 




















Suture. Axial Line. Transverse Diameter. 
L 
| 
Stages ] qe LIL Glabella, Py Basal Middle. | Anterior. | 
Sdles|Salosl3 | SA | Distorti 
of É 58 28 ae Em sal NE Lee!) Distortion. 
Growth. 2S| se SA |es|as| § és lee lsa| Slee! 5 
EU FÉES 2 |** [22 | 22/22 S 18 4 
| | A Lee AS) & | Ss) & 
Se is € Ex Eee mer Folle | 
| | | | 
10-9 millimetres. *06 |°53 “24 ||-21 |-08 |-12 (753 “08 ||-32 |:50 |-47 55 -85 | 1 slight. 
| | | a 
15-4 Se (2:08 ?-46 |-29 |?-21 ||-14 |-06 |-13 |:58 |*06 |?-46 |?-46 |?:46 |-58 |?:37 |-75 | © 
| (-62)| | | (83), x 
21:8 < [°12 |-50 |°22 |-21 ||‘15 |-10 |°12 |°56 06 ||-32 |°56 |*51 |°51 |-30 |°75 | + ? 
| ar 
221 £ 12 |:49 |?:27 (2-23 ||°18 |-09 |°16 |°51 |-05 ||-34 |-53 |°47 en +27 |°78 Na slight. 
i 1 




10.9 MILLIMETRES.—Glabella—At this period the glabella is already quite wide, a 
characteristic feature of this form, and the dome well developed. The fourth furrow is as yet 
less than half way from the front of the dome. 
Occipital Ring.—This exhibits the usual predominance over other parts of the shield in 
the early stages of the growth. The width is considerably more than one-third of the 
length. The occipital spine has not been observed at any stage in the growth of this 
variety. 
The posterior margin is narrower and weaker than at the corresponding stages of any 
of the proceding forms. 
The fixed cheek is well developed and the ocular lobe proportionately longer than at 
later stages of growth. 
Sculpture—The bands of tubercules, the raised lines on the glabella, and the granula- 
tion of the general surface of the test can already be very easily recognized with a moderate 
power. 
15.4 MILLIMETRES (Fig. 3)—Glabella:—Allowing for the absence of flattening, this part 
is larger than in the preceding stage, and the fourth furrow is about three-fifths from the 
front of the dome. 
The sculpture is very distinct and characteristic of this variety. 
21.8 MILLIMETRES (Fig. 1)—The anterior margin at this age shows no space between 
the glabella and the fold. à 
o 

is 

