﻿Vol. 66.'] THE CAMBRIAN ROCKS OF COMLEY. 47 



the corresponding feature in his Avalonia manuelensis — ' inoscu- 

 lating raised lines giving the appearance of pits V 



Free cheek. — One fragment [584] of a free cheek presenting the 

 same surface-characters has been noticed. It may be described as 

 spherically triangular ; small ; and having the genal angle produced 

 to a short spine, which is oval in cross-section. I have attempted 

 to show in PL VI, fig. 8 the modification of the surface -characters 

 as they approach the outer margin. The meshes of the network 

 become squeezed out and elongated, until little is to be seen but 

 a set of irregular raised lines. 



Locality and horizon. — Comley ; from the uppermost band 

 of the grey limestone, at the excavation 200 yards south of the 

 quarry. 



These two species have many points of resemblance with 

 Micmacca (?) plana, Matthew. 2 The large glabella ' descen ding- 

 gradually at the front, and bordered by a distinct, but faintly im- 

 pressed dorsal furrow,' the faint occipital and glabellar furrows, the 

 slight convexity of the cheeks, and the proportions between their 

 width and that of the glabella, are all points in common. It seems 

 evident that the three species are congeneric. 



^ \t\i Avalonia manuelensis, Wale, there is a striking resemblance 

 in the characters of the test of Mohieana elavata ; and with Avalonia 

 acadica, Matthew, 3 there is a general resemblance in the view from 

 above, but the peculiar grooves on the line of the ocular ridge are 

 absent, and the frontal limb is more extended. 



Concluding Remarks. 



It would be premature to discuss at length the exact age of the 

 beds which have yielded the trilobites here described, until the 

 remainder of the fauna has been more fully worked out. I would, 

 however, call attention to the fact that the specimens of Protolenus 

 occur at Comley a little above the horizon of Olenellus (Holmia) 

 callavei, Lapw., and below the lowest local representative of the 

 genus Par ad oxides. This is in entire agreement with the position 

 assigned to the genus by Mr. G. F. Matthew, at his type locality 

 at Hanford Brook. 



It also seems of interest to note that several of the Comley forms 

 from the Olenellus and the grey limestones, namely, Microdiscus 

 Jielena, Wale, M. speciosus, Ford, 31. lobatus, Hall, and Ptychoparia 

 (?) atileborensis, Sh. & F. (as also Agraidos strenuus, Bill., which 

 seems closely related to the Shropshire Strenuella), are found in 

 America low down in the Olenellus Zone, the last two being quoted 

 by Dr. Walcott 4 from the base of the Olenellus Zone at Manuel's 

 Brook (Newfoundland) . 



i Proc. U.S. Nat. Mus. vol. xii (1889) p. 44; and 10th Aim. Rep. U.S. Geol. 

 Surv. 1888-89 (1890) p. 64G & pi. xcv, figs. 3, 3 a. 



* Trans. N.Y. Acad. Sci. vol. xiv (1895) p. 143 & pi. xi, figs. 2 a-2 b. 



3 Ibid. p. 140 & pi. ix, fig. 5. 



4 10th Ann. Rep. U.S. Geol. Surv. 1888-89 (1890) pp. 650, 654. 



