Vol. 62.] BY DR. J. W. EVANS IN BOLIVIA . 427 



The width of the thoracic axis and the shape of the free cheek, 

 render it almost certain that the specimens belong to the genus 

 Peltura. The remains are not sufficient, however, for specific 

 description. 



Locality (1). Three miles north-east of Pata. 



Stmphysurus Apolonista, 1 sp. nov. (PI. XL, figs. 2 & 3.) 



Head semicircular, very convex, forming nearly a quarter of a 

 sphere. Glabella smooth, not elevated, occupying about one-third 

 of the whole width of the head, and reaching forward to the 

 anterior margin ; the axial furrows which define the glabella are 

 well-marked, they converge gently forwards until within a short 

 distance of the anterior margin, where they again diverge and at 

 the same time become slightly shallower. Occipital furrow well 

 defined, both on the glabella and on the cheeks. Eyes fairly large, 

 prominent, placed very close to the glabella, and about half way 

 between the frontal and posterior margins. Facial suture in front 

 of the eye indistinct, but appearing to run nearly parallel to the 

 axial furrows; behind the eye, it is deflected outwards and meets 

 the posterior margin within the genal angle. The genal angle was 

 apparently rounded, the cheeks not marginate. 



The tail is highly convex ; it appears to have been nearly semi- 

 circular, and not marginate. Axis conical, raised, reaching to 

 the posterior margin, where it terminates in a blunt point; it bears 

 a number of annulations, but (probably in part on account of the 

 nature of the matrix) these are too indistinct to be counted. The 

 lateral lobes are smooth. 



This form is not unlike SympTiysurus. incipiens, Brogger 2 ; but 

 the greatest constriction of the glabella is more forward than in 

 that species, the eyes are smaller, and the tail was apparently 

 not marginate. As regards the last character, however, there is 

 room for doubt, since the only specimen of the tail is obviously 

 incomplete. 



Locality (2). About a mile north-by-west of Apolo. 



Teintjcleus boliviensis, sp. nov. (PI. XL, figs. 4 & 5.) 



Only the head of this little species is known, and in outline it 

 forms a segment of a circle. Glabella pyriform, narrow posteriorly, 

 broad in front, very convex and prominent, standing high above 

 the level of the cheeks ; anteriorly it ends abruptly and almost 

 vertically at the fringe, upon which it does not encroach ; two pairs 

 of short glabellar furrows near the base ; occipital furrow deep. 

 Cheeks triangular, slightly convex, with deep occipital and marginal 

 furrows. Fringe very narrow, and nearly uniform in width through- 

 out : owing to the coarseness of the material in which the specimens 

 are preserved, the structure of the fringe is not distinct, but in one 

 or two cases traces of the perforations are visible. 



1 Apolonista = an inhabitant of Apolo, common gender. The name was 

 kindly suggested to me by Dr. Evans. 



2 ' Die Silurischen Etagen 2 & 3 ' Christiania 1882. p. 58 & pi. i, figs. 1 & 2. 



