TEfj; FAUNA OF THE ST. JOHN GEOUP. 143 



Other distinctions in the characteristics of the head-shield are briefly contrasted 

 in the table on the characters of the Ptychoparinae of Division 1, given on a previous 

 page. 



Ptychoparia Linnarssoni (PI. II, figs. 1 a to m.) 



Liostrucus Linnarssoni, Brogger (1818), Paradoxidesskifrene vid Krekling, p. 4t, Tab. 

 Ill, fig. 4. 

 " " Linnarssou (1883), Undre Paradoxides lagreu vid Andrariim. 



The history and description of this species can be best shewn by giving the full and 

 careful accounte of Messrs. Brogger and Linnarsson. The former has given the following 

 diagnosis of the species : — 



" L crusta impresso-punctata, capita valde convexo, fronte conica utrinque sulcis obso- 

 letis 3, annulo occipitali mutico, puucto elevato ornato. Pygidium lenticulare paulum, 

 rachi convexo e segmentis 5, apice binodoso, sulcis lateralibus 3, distinctis." 



The more complete descriptions of this species, in the articles above cited, so exactly 

 describe the Acadian form that, with the approval of Dr. Brogger, I have quoted them 

 here : — ' 



Liostracus Linnarssoni, u. sp. (Linnarsson L. aculeatus partim), (PI. Ill, fig. 4.) 



" This species is distinguished from the former (L. acnlentus, Aug.) by the want of a 

 point on the neck joint, which is provided only with a small tubercle ; by the more 

 prominent form of the head ; by the more conical glabella, provided on each side with 

 three faint furrows. The free cheeks end in a short genal spine. The pygidium is rather 

 different from that of L. niicropthalmns, Aug. ; it is small, leus-forraed, and has a strongly 

 convex rachis, which is plainly divided into five joints ; the last joint is in two parts, 

 from which the rachis appears to end in two tubercles. The side lobes possess two plain 

 furrows. 



" Size. — Head's length, commonly 9 to 12 mm. ; Pygidium — breadth, 10 mm. ; length, 

 4 mm. 



" Horizon. — Frequent at Krekling, in the lower ^lart of Stage 1 c. Distributed in 

 Sweden and Norway with Paradoxides Tessini.'" 



Dr. Gr. Linnarsson subsequently gave the following amended description of this 

 species from examples found at Andrarum, in Sweden : — 



" 1869, Liostracus aadealus (non Aug.), Linnarsson, Om Vestergotland Cambriska, &c., 



p. 71. 



" ISYS, " " Kjerulf, Sparagmitfjeldet, p. 84, fig. 14. 



"1818, " Linnarssoni, Brogger, Paradoxidesskifrene vid Krekling, p. 47. 



Tafl. Ill, fig. 4. 

 " " aculeatus, (non Aug., Brogger, loc. cit., p. 46, Tafl. Ill, fig. 3. 



" Caput convexum. Frous ovata antice rotundata, sulcis utrinque ternis, obsoletis. 

 Genœ fixœ xandique modice et regulariter couvexte. Annulus occipitalis aculeis armatus. 

 Limbus capitis ante frontem hand reflexus. Pleurae thoracis duabus seriebus tubercu- 



' " Om Paradoxidesskifrene ved Krekling, p. 47 (1878.) 

 ^ De Undre Paradoxideslagren vid Andrarum, .p. 23 (18S3.) 



