THE FAUNA OF THE ST. JOHN GEOUP. 121 



similarly ornamented. In the free cheek of our best example of this species, very little of 

 the upper surface of the folded part has been preserved ; this has a few distant striae, but 

 the under side has more numerous striae, about twenty in number ; these are distinct, 

 parallel to the sides, distant on the outer side and middle, but more crowded toward the 

 inner edge of the fold. A few striae only have been observed on the upper surface of the 

 marginal fold ; the genal spine also carries a few strong striae on its tipper surface. In 

 other parts of the body the outer surface of the test is smooth. The margin of the quadrate 

 part of the hypostome carries about six sharp striœ ; fainter striae appear on the front lobe 

 of the hypostome ; and more distinct, frequently anastomosing striae cover the lateral 

 extensions of this lobe. 



Size. — Length, from the apex of the head-shield to the tip of the pygidium, fifteen 

 inches (= 39 cm.) Width of head-shield, 12 inches (= 31 cm.) Length of head-shield, 

 4| inches (= 11| cm.) Width of thorax, 8J inches (= 22 cm.) Length of thorax, 8| 

 inches (= 22 cm.) Width of pygidium (posterior end) If inches ( 4Jcm.) Length of 

 pygidium, 1| inches (= 34 cm.) Surface of the whole body, about llY sq. in. 



Examples of separate thoracic segments have been found, of which the rachial part is 

 as long and wide as the front ring in the example figured, and the pleural part a fifth 

 longer than in the specimen figured. It is evident, therefore, that this nearly complete 

 specimen does not exemplify the full size of the species. 



Sea;. — Until more numerous examples of this species are known, we can only indicate 

 features, which might lead to the surmise that the example figured is the broad form of 

 the species. Primarily it may be remarked that the glabella is very broad, and the lobes 

 only obscurely marked. But the main feature to be depended upon as a guide to the sex, 

 is the great comparative width of the rachis of the thorax, and the correspondingly short 

 pleural extensions. This, with the shortened form of the body, and the absence of pleural 

 extensions in any part of the thorax, as well as the rapid narrowing of the posterior part of 

 the rachis, are strong indications of the broad form. The short genal spine, accompanied 

 by short pleural points, also indicates this as probably the broad form. 



Furthermore, there are loose segments of the thorax found in the same shales, which 

 exhibit a différent proportion of form in the thorax, the ring being as long, and the pleurae 

 considerably longer. The associated genal spine is also at least half an inch longer than 

 that of the individual figured. 



Horizon und Locality — In the grey shales of Div. (or Stage) Ic at Portland, N. B. 



Found by W. D. Matthew. 



This trilobite is honored with Her Majesty's title, as that of a sovereign, who, during 

 the many years of her reign, has greatly fostered science and art. 



In this species we appear to have one which exceeds all other known Paradoxides in 

 size. The example figured is exceeded in length by two European trilobites, viz., Megalaspis 

 aadicauda and Asaphus Barrandei ; but, in the historical notes at the beginning, it was shewn 

 that these species were probably narrower than Paradoxides regina. This is no doubt the 

 case with M. aculicauda, and the dimensions of the pygidium of this species described by 

 Brogger, if xised as a basis for estimating the size of the whole animal, would give a 

 surface area of about 100 square inches, while the surface area of the figured example of 

 Paradoxides regina is about 11*7 square inches. 



Sec. iv, 1887. 16. 



