Dr. F. R. Cowper Reed — The genus Honalonotus. 273 



JZ rudts is an unsatisfactory species owing to the impossibility of 

 drawing up a proper diagnosis from the original material. 



The pygidium (No. -3%- Mus. Pract. Geol.) figured by Salter in 1865 

 (op. cit., pi. X, fig. I'd) from the " Caradoc Grits of Cressage, 

 Shropshire ", as probably referable to H. rudis, must certainly be 

 separated, and may belong to the new species H. hiserratus Eeed MS. 

 (the description of which awaits publication), but its edges are broken 

 and imperfect. 



The other British species referred by Salter to the second section 

 of Brongniartia are the two from Budleigh Salterton pebbles 

 described as S. Brongniarti, Deslong.,^ and H. Vicaryi, Salter.^ 

 A third ^ unnamed species is described by Salter from the same 

 locality, and a fourth from Gorranhaven,* both the latter being 

 represented only by pygidia. According to Bigot,* Salter's 

 M. Bro7igniarti, Desl., is not the same as Deslongchamps' type, 

 but is referable to H. serrattts, de Trom. The figures and description 

 ofIf.viilca7ii (Murchison), promised by Salter (op. cit., p. 113) have 

 never been published ; it is stated® " to occur in the volcanic grit on 

 the west flank of Corndon Mountain in a ravine east of Middleton ", 

 but I have not been able to trace the specimen. 



The species of Homalonotus from the Gres de May, Normandy, 

 including those from the British pebbles in the Budleigh Salterton 

 Triassic conglomerate, and also those from Gorranhaven, belong to 

 a group somewhat distinct from the typical Brongniartia, though 

 (as stated above) Salter put them in his second section. They seem 

 to be the earliest representatives of the genus, apart from any of the 

 questionable genus Neseuretiis. The characteristics of the group are 

 the strong trilobation of the thorax and pygidium, and the short 

 transverse or semicircular shape of the pygidium, together with its 

 composition of few segments, and its vertical or steeply inclined but 

 not completely infolded doublure. It may also be mentioned that 

 the pleurae on the pygidium are occasionally separated by furrows 

 right up to the edge of the doublure, and sometimes show traces 

 of division at their ends, and that the furrow which marks off the 

 articulating band at the front end of the axis is continued laterally 

 as a strong furrow across the large bevelled articulating facet at the 

 anterior lateral angles of the pleural lobes. In the case of the head- 

 shield it appears that the facial sutures cut the lateral margins 

 slightly in front of the genal angles, which are well rounded; the 

 glabella is parabolic, semioval, or rounded-trapezoidal, and the axial 

 furrows are not sinuated as in H. hisulcatus. The facial sutures 

 unite in front marginally or just inside the margin in a regular 

 uninterrupted curve, which may or may not be flattened. Most, if 



' Salter, Quart. Journ. Geol. Soc, vol. xx, p. 290, pi. xv, figs, la, 6, 1864 ; 

 Mon. Brit. Trilob., p. 110, pi. x, figs. 15-17 ; pi. xiii, fig. 9. 



" Ibid., p. Ill, pi. xiii, fig. 10. 



3 Ibid., p. 112, pi. X, fig. 18. 



* Ibid., p. 112, woodcut, fig. 26. 



'^ Bigot, Bull. Soc. Geol. France, ser. Ill, vol. xvi, p. 427, 1888. 



" Murchison, Silur. Syst., 1839, p. 663; id., Siluria, 2nd ed., 1859, pi. ii, 

 figs. 3, 4. 



DECADE VI. — VOL. V. — NO. VI. 18 



