106 G. F. MATTHEW ON ILLUSTRATIONS OF 
anterior lobe of the glabella.” The writer has met with a form which appears to be a variety 
of the species with vertical interrupted plates on the front of the glabella. 
Var. Loricatus (Fig. 19) 
The anterior margin is arched moderately around the front of the glabella. The 
marginal fold is almost twice as wide at the extremity as in front of the glabella. The 
flat area is small and short. 
The glabella is broad and elevated in front. The anterior slope of the dome is 
ornamented with about four rows of elevated ridges or plates, of unequal length 
Jaterally ; those of the three outer rows are generally longer than those of the inner 
row, some of which are so short as to resemble tubercules rather than plates; 
the length of the plates in the outer row is about equal to the width of the flat area 
of the anterior margin. Within the rows of plates the dome of the glabella is 
decorated with rows of tubercles parallel to the rows of plates. The elevated 
ridges are hollow, and consist of an upward folding of the substance of the test, there 
being a cavity on the inside of the test corresponding to the ridge on the outside. 
Sculpture—The anterior marginal fold has a few raised, longitudinal lines near the 
extremity, and the whole surface of the test is covered with minute granulations which 
are just discernible with a lens of 1 in. focus. 
Locality, Portland, N. B. In Division 1 c. 
Size—The fronts of two cephalic shield were found: of these the larger indicated a 
buckler about half an inch long. 
Conclusions. 
Though it has not been possible to exhibit a complete series showing the stages of 
growth of any of the trilobites of the St. John group, a sufficiency has been obtained to 
show that the growth and development of the young of different species led upward from 
embryonic forms similar in certain general features to those of Sao hirsuta and Olenellus 
(Elliptocephalus) asaphoides These features of advancement toward maturity in the St. John 
Paradoxides may be briefly expressed as follows :— 
1. Widening of the extremities of the anterior marginal fold, and absorption of the 
central part of the flat area. 
. Enlargement of glabella in all directions and retreat of the fourth furrow from 
the front of the glabella. 
3. Transverse lengthening and axial condensation of the occipital ring. 
4. Enlargement and strengthening of the posterior margin. 
5. Longitudinal contraction of the eyelobe. : 
Of these modifications of the cephalic shield perhaps the changes in the glabella were 
of the greatest moment. The way in which the enlargement of this portion of the shield 
took place at the different moults is perhaps indicated by the peculiarities of two of the 
forms. 
In variety or sub-species, quacoensis, there is a band around the base of the dome of the 
glabella from which the raised concentric lines are entirely absent, and the smoothness of 
the surface is affected only by minute granulations. This smooth band, it may be supposed, 
is a late addition to the glabella; it is considerably wider (3} mm.) at the insertion of the 
bo 
