270 Br. F. R. Coivper Reed — The genus Homalonotus. 



figured as further examples of the genus the Trilobites B. platy- 

 cephala ^ {=11. Dekayi, Green) and B. isotelea * ( = Asaphus 

 platycephalun, Stokes). Vogdes ^ puts B. platycephala, Eaton, as 

 a synonym of H. delphinocephalus, Green. It is obvious from these 

 facts that the name Bro7igniartia caunot be retained for Salter's 

 group of Homalonotus. 



The type of the group must now be considered. This species, 

 B.. hisulcatiis, was founded by Salter* on specimens ia the Geological 

 Society's Collection and in the Woodwardian [Sedgwick] Museum, 

 Cambridge. The first figured specimen, a middle-shield (op. cit., 

 fig. 24), is stated in the text of McCoy's Synopsis to be from the 

 " Caradoc Sandstone, Wittingslow, near Acton Scott, Shropshire", 

 but in the explanation of the plate is stated (in error) to be from 

 " S.W. of Pwllheli". The imperfect thorax and pygidium depicted 

 in his fig. 26 and the separate pygidium (fig. 27) are from the same 

 locality in Shropshire, and all these three specimens are in the 

 Geological Society's Collection, now in the British Museum (Natural 

 History), South Kensington. The specimens from which figs. 25 and 

 28 were drawn are in the Sedgwick Museum, and came from the 

 Welsh locality south-west of Pwllheli. Three other specimens 

 (figs. 29-31) are referred by Salter to a variety ^ tm'nor, and are 

 also at Cambridge. But the chief point to be emphasized is that 

 the species is undoubtedly founded on the Shropshire specimens, and 

 it is by them that its characters are fixed. 



Salter* in his monograph in 1865 figured several examples from 

 other Welsh localities, but stretched the limits of the species in 

 including some of them ; the first figures on his plate (pi. x, 

 figs. 3, 4) are of those specimens from Wittingslow which he had 

 used in his previous description in 1852 and had there figured. 



In his first subsection of Brongniartia Salter put also his species 

 S. Sedgioicki and H. Edgelli ; the former was founded on two broken 

 middle-shields in the Woodwardian Museum and calls for no special 

 mention in this place, except with regard to the much flattened and 

 wide curvature of the union of the facial sutures, which makes the 

 head-shield (as Salter says) truncate in front and unusually broad. 

 The second species was founded on a pygidium, but a doubtful 

 middle-shield from Horderly was also ascribed to it. 



We must, however, return to a consideration of the characters of 

 the typical S. hisidcatus, for Salter's first description in 1852 is too 

 brief, and his second description in 1865 is inaccurate, for it includes 

 the ambiguous Welsh specimens, some of which at any rate ought 

 probably to be separated off. "Confusion is introduced by Salter's 

 conflicting statements that the " body is scarcely trilobed " (p. 104) 



^ Eaton, op. cit., pi. ii, fig. 20. 



2 Ibid., pi. ii, fig. 22. 



^ Vogdes, Bibliogr. Palasoz. Crust. (Occas. Papers Calif. Acad. Sci., iv, 

 p. 311, 1893) ; Waller, Bull, iv, pt. ii, Nat. Hist. Surv., Chicago Acad. Sci., 

 1907, p. 200. 



\ Salter, Appendix to M'Coy's Syn. Brit. Paleoz. Foss. Woodw. Mus., 1852, 

 p. V, pi. IG, figs. 24-8. 



* Id., Men. Brit. Trilob., 1865, p. 105, pi. x, figs. 3-10. 



