52 G. P. MATTHEW ON TUB 



have a low ridge along the centre ; they are divided from the anterior lobe by a strait 

 furrow running backward and outward. The central body is conical with rounded 

 corners ; it consists of an oval anterior lobe, pointed behind, and two crescent shaped 

 posterior lobes. Behind these lobes is a broad posterior fold terminated at each extre- 

 mity by a short spine directed outward ; this part appears to have been under the 

 occipital ring. 



A young individual of this variety, 85 mm. long, complete, except for the absence of 

 the movable cheeks, shows some differences from the adult. The glabella is proportion- 

 ately longer and narrower, and there is a somewhat wider space ^between the glabella 

 and the anterior marginal fold. This individual had ten joints in the thorax, of which 

 the six anterior ones were furnished with tu.bercles on the rachis. These tubercles were 

 not noticed on all the front joints of adult thoraces, and perhaps tend to become obsolete 

 during growth. 



Sculpture. — The appearance of the surface of the test in this variety is much the same 

 as in P. her es. 



Size. — Middle piece of head, length, *7J mm. ; width, 14 mm. Movable cheek, length 

 (including spine), 11 mm. ; width, 2>\ mm. Hypostome supposed to belong to this species, 

 length, 6| mm. ; width, 7 mm. Pygidium, length, 4 mm. ; width, 8 mm. 



Horizon and Locality. — In the black slates of Div. 3 ^ at Navy Island, St. John Harbov;r. 



This variety differs from the typical form, as figured by Brogger, in having a propor- 

 tionately wider glabella and fixed cheeks, and in having one joint less and one pair of 

 spines less in the pygidium. 



Var. grandis, u. var. (PI. XIII, fig. T.) 



A pygidium which is large enough to be that of Pellura scaraheoides, but does not 

 agree with those figured for that species, was found in the same bed with the above 

 species. 



Form semicircular, enclosed by a border fold, armed on each side with three or four 

 slender spines.' Eachis broad, of four segments, of which the first bears a small tubercle. 

 Side lobes with three ribs, creased diagonally by furrows ; the side lobes meet behind 

 the rachis. 



Size. — Length, 8 mm. ; width, 15 mm. 



Horizon and Locality. — In the black shales of Div. 3 6 at Navy Island, St. John 

 Harbour. 



This pygidium in its features is intermediate between that oï Parabolina Jieres (type) 

 and Protopeltvra acanthura (type). It has one joint less in the rachis than the former, and 

 one more than the latter. The broad rachis is like that of Prolopeltura, but the more 

 numerous joints of the rachis, and the very slender spines on the margin, seem rather to 

 ally it with the above Parabolina. The oirtline of the margin is quite different from that 

 of the pygidium of Pellura scaraheoides, and there is one joint more in the rachis than in 

 that species. 



• From the position of four spines at the back of the pygidium it is inferred that there are probably two otliors 

 on each side towards the front. 



