98 G. F. MATTHEW ON ILLUSTRATIONS OF 
that of P. etemenicus ; it is also more strongly arched along the middle ; is lenticular rather 
than rectangular in outline, and the spine is more prominent. 
Sculpture —The general surface of the shield is smooth, even when viewed with a lens 
of one inch focus. But there are two bands of small tubercules, as in P. eteminicus, which 
seem more distinct in the variety, owing to the smoothness of the shield elsewhere. 
1 append measurements of a few heads to show the peculiarity of form, etc. The table 
is in all respects the counterpart of that on a previous page showing the stages of growth 
of P. eleminicus. 
MEASUREMENT OF CEPHALIC SHIELDS. 








Suture. Axial Line. Transverse Diameters. 
Stages Aad ales Glabella. |, | Basal. | Middle. | Anterior. 
, a es AE = =e peste: FE ae Thee AE Distortion. 
owth. 2S) S>| BS as 2 aS lem le) oo] = | esg| S 
row £a al << |28|l8 ES es 5 <q HE FE 2 Ee 2 
——— = gi ER fae ee Rs ns © | 
6-4 millimetres.|‘07 |*40 |:25 |-15 ||-15 |-05 |-10 |-45 |:15 |/-30 40 |*45 |°45 1°35 |-65 | \ 
13°5 07 |*43 |-29 |-19 ||-14 |-10 |-12 |-52 |-10 ||:29 |*45 |:43 |-52 |-29 |-65 | + 
1999 x 08 |-44 |-26 |-19 ||-16 |-08 |-10 |-55 |-10 ||-35 |-45 |-45 |-50 |2:32|-70 | + slight. 
35°3 2 09 |-39 |-22 |-19 ||-15 |:08 |-10 |-55 |-06 ||-29 |-40 |-40 |-46 |-23 |-69 | \x 
37°1 5 10 |-38 |-24 |-16 ||-16 |.09 |-11 |-59 |-06 ||-30 |*47 |-38 |-53 |-23 |-74 ats 



















Growth and Development of the Young. 
Although this variety has not been found of so small a size as P. eteminicus, those 
observed show a similar development of the test during growth. 
6.4 MILLIMETRES (Fig. 6).—At this stage there are marked differences from the adult 
form. 
Anterior margin —The marginal fold is slightly wider at the ends than in the middle, 
and the flat area goes around the front of the glabella, where it is as wide as the mar- 
ginal fold. ‘ 
Glabella—The dome is more prominent than in P. efeminicus of similar age ; and the 
fourth furrow is behind the line of the eyelobe, and already nearly half way from the front 
of the dome. 
The occipital ring is very wide in the middle, with an elevated central half, as in the 
young of P. eteminicus, but the spine is set further back on the ring. The posterior margin 
is narrow and weak when compared with the adult form. 
Fixed cheek.—The cord of the eye-lobe is four-sevenths of the sum of the measurements 
of the facial suture. 
Sculpture —Parallel raised lines are distinctly seen on the anterior marginal fold and 
on the dome of the glabella. 
13.5 MILLIMETRES.—-In this there are decided changes from the earlier moult, all in the 
direction of the adult form. 
, wa % 
