58 Proceedings of the Royal Society of Victoria. 



sp.,* curving as it does outwai'cls anterior to the eyes, and from 

 the glabella, will, I think, at once debar the Victorian fossils 

 from incorporation in that genus, to say nothing of the entire 

 margin of the pygidium in Ptychoparia. It is true that in a few 

 species of the latter a glabella and fixed cheeks occur akin 

 somewhat to those of Dinesjis., for instance in the Lower 

 Cambrian P.? Fifchi, Walcott.f The latter, however, departs 

 in a very marked manner from the regular Ptychoparia type, 

 and resembles our fossils in the " elongate, unfurrowed glabella, 

 wide fixed cheeks, and granulose surface," and apparent absence 

 of glabella grooves. 



In Liostracus the similai-ity in the square-oblong outline, and 

 unfurrowed state of the glabella in the type species, L. aculeatus, 

 Angelin, and L. muticus, Angelin, | to that in Dinesus is strong, 

 but the facial suture is organised on the same plan as in Ptycho- 

 paria., although, perhaps, to a lesser extent. Still, there is no 

 trace either in Ptychoparia or Liostracus of the circumscribed 

 lobes, and the pygidium in the latter again presents an entire 

 margin. 



Solenopieura, as exemplified by the type species S. Jwlometopa, 

 Angelin,§ possesses facial sutures as difFei'ent to those of Dinesus 

 as those of PtycJwparia. But Mr. Walcott has described two 

 doubtful species, 6". t 7iana, Ford, and S. ? tuinida, Walcott, || 

 that certainly appear to be near our Trilobite, although Lawer 

 Cambrian forms, and which he admits " appear to belong to a 

 genus distinct from the typical species of Solenopieura." One in 

 particular (6". t tuniida) has small circumscribed lobes at the 

 hinder portion of the glabella, moderately straight and parallel 

 axial furrows, and small eye-lobes, but with hxed cheeks hardly 

 as wide as in our specimens, and no frontal furrow to speak of. 

 S. ? nana, on the other hand, possesses the latter, but no circum- 

 scribed lobes. In typical Solenopleurce the margin of the 

 pygidium is again entire. 



e See Barrande, S.vst. Sil. Bohoinc, li>.">-2, I., t. 14, f. 1-7 ; Walcott, Bull. U.S. Geol. Survey, 

 1884, X., t. 6, f. 4. 

 t 10th Anil. Report U.S. Gcol. Survey, 1890, p. 650, t. 96, f. .'5. 

 X Pal. Seandinavica, 1854, Pt. II., p. 27, t. 19, f. 2 and 3. 

 §Pal. Seandinavica, Pt. II., 1854, p. 26, t. 18, f. 8. 

 II 10th Ann. Report U.S. Geol. Survey, 1890, p. 658, t. 98, f. 1 a-c, 2, 3, 3a. 



