428 MR. P. LAKE OF TRILOBITES COLLECTED [Aug. 1906, 



The genus Trinucleus appears to be new to South America. 

 Prof. Kayser 1 has described and figured several remains of Ampyx 

 from Potrero de los Angulos in the Argentine Republic ; but, with 

 this exception, no representative even of the family, so far as I am 

 aware, has hitherto been recorded from South America. 



In its narrow fringe and convex pyriform glabella, Trinucleus 

 coscinor7iinus, Ang.,from the Chasmops-Limestone of Sweden, some- 

 what resembles the species just described ; but in the former the 

 glabella is not so prominent, and it is much more constricted 

 towards its base. 



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



Ooygia sp. (PI. XL, figs. 6 & 7.) 



From the third locality, on the River Caca, came a number of 

 fragments of tails. These were subtriangular in outline, with a 

 very broad and well-defined margin, and must have attained a 

 length of three-quarters of an inch. Axis narrow, reaching to the 

 margin, and, so far as can be seen, without annulations. Lateral 

 lobes but slightly arched, marked by faint ribs which are sometimes 

 obsolete. 



From the same locality comes a small hypostome, about as broad 

 as it is long, ending in an obtuse point ; a strong curved furrow 

 passes transversely across, a little within the distal margin, and a 

 second short furrow seems to cut off the extreme point. 



To judge from the tails alone, the species might belong to either 

 Niobe or Ogygia, or even to the genus Asaphus. But the hypo- 

 stome seems to be distinctly the hypostome of an Ogygia ; and it 

 closely resembles that of Ogygia Selwyni, Salter. 



Prof. Kayser 2 has already described and figured the tail of an 

 Ogygia from Argentina, and he draws attention to its resemblance to 

 0. Selwyni, Salter. 



Locality (3). River Caca. 



Phacops cf. aebtjtetjs, Lake. (PI. XL, fig. 8.) 



1904. Phacops arbtiteus, Lake, ' The Trilobites of the Bokkeveld Beds ' Ann. 

 S. A. Mus. vol. iv, p. 203 & pi. xxiv, figs. 2-4. 



Of this form only a single specimen, showing the central portion 

 of the head, has been found. The glabella is elongated, nearly 

 parallel-sided, rounded in front, and decidedly convex transversely ; 

 it bears a number of scattered tubercles. The anterior pair of 

 glabellar furrows is strongly inclined forwards, and is quite distinct ; 

 the second pair is not so clear, but this is apparently due to the 

 imperfection of the specimen ; the third pair is much the strongest 

 of the three and is nearly at right angles to the axis. The frontal 

 lobe of the glabella is very long, forming about one half of the 



i i Primordiale & untersilurische Fossilien aus der Argentinischen Republik * 

 Palseontographica, Suppl. iii, Lief. 2 (1876) p. 24 & pi. i, figs. 25-27. 

 2 Ibid. p. 12 & pi. i, fig. 20 [non pi. ii, as stated on that page]. 



