﻿26 MR. E. S. COBBOLD OX XRILOBITES FROM [Feb. I9IO,. 



Nearly allied also is the same authors second Siberian species.. 

 Ptyclioparia meglitzkii? which, however, has weak glabellar furrows 

 and differently formed fixed cheeks. 



Pt. (?) prospectensis, Walcott, 2 "has a circular swelling in front of 

 the glabella of equal elevation with it, and a fixed cheek extending 

 forwards, with prominent eye-lobes on the outer margin. This form 

 would seem to be a more distant ally of our species, but it has aiii 

 anterior border to the frontal limb. 



Pt.(?) liiinarssoni* Walcott (not the Pt. linnarssoni, Brogger). is- 

 another species with a swelling on the frontal limb in front of the 

 glabella, and elevated fixed cheeks extending forwards with a rather 

 prominent eye-lobe, but the general shape of the cranidium and the 

 widely diverging posterior branches of the facial suture give a very 

 different aspect, to the head-shield. It, too, has an anterior border 

 to the frontal limb. 



A still more divergent form has been described by Dr. Walcott as 

 Pt. (?) pemasutus* in which the glabella has much the same general, 

 shape as the Comley species ; but in this case there is an extrava- 

 gantly enlarged frontal limb, which runs out forwards into a. 

 point and is only slightly convex. It is somewhat reminiscent of 

 Anomocare acwminatwm, Aug. 



In all these forms, which have been doubtfully referred to Ptt/cJio- 

 paria, there seems to be a relic of an aboriginal trilobation of the 

 anterior portion of the head-shield. 



Micmacca, Matthew. 



Under this name Mr. G. F. Matthew describes 



' A group of trilobites with large, rather prominent, cylindrical glabella,. 

 which extends almost to the front of the shield ; and with continuous eye-lobes 

 and a short, direct posterior extension of the dorsal suture.' (Trans. N.Y.. 

 Acad. Sci. vol. xiv, 189r>, p. HI.) 



There are several forms derived from the Olenellus Limestone 

 of Comley which I provisionally refer to this genus, although they 

 are almost as closely allied to ElUpsoceplialus, Zenker, and again 

 have affinities with some forms of Anomocare, Angelin, and with. 

 Mr. Matthew's suggested subgenus (Strenuella) of Agmulos, Corda. 



The true generic position of these Comley fossils can hardly be 

 ascertained, until the thoracic segments and pygidia are forthcoming. 



For the present, I divide them into two species : one a very 

 minute form, and thereby differing strongly from Mr. Matthew's 

 type species ; the other of moderate size, and presenting several 

 variations, so that it is possible that a third or even a fourth species 

 may be represented. 



Their occurrence in the same bed of rock with Olenellus (Holmia) 



1 Mem. Acad. Imp. Sci. St. Petersb. ser. 8, vol. viii, no. 10 (1808) p. 22 & 

 pi. i. fig. 2. 



- ' Palceontologv of the Eureka District' U.S. Geol. Surv. Monogr. viii,. 

 (1884) p. 46 & pi." ix, fig. 20. 



3 Ibid. p. 47 & pi. ix. figs. 18, 18 a. 



4 Ibid. p. 49 & pi. x. figs. 8, 8 a, 8 b. 



