﻿Yol. 66.~] THE CAMBRIAN ROCKS OF COMLEV. 27" 



would seem to indicate that they come from a relatively earlier 

 horizon than the Acadian forms, and their alliances with other 

 genera suggest an earlier stage in development. 



MlCMACCA (?) ELLIPSOCEPIIALOIDES, Sp. nOV. (PL YII, figS. 8 & 9 & 



pi. Yin, fig. i.) 



This species is founded upon five specimens in my own collection,. 

 and upon a similar number from the British Museum (Natural 

 History) collection at South Kensington; and I would here wish 

 to acknowledge my indebtedness to the Keeper of the Geological 

 Department for the loan of the latter specimens. 



I take as the type-specimens [413] of my own collection and 

 [J 12905] from the British Museum, and to this typical form speci- 

 mens [955, 200, & 201] are also referred. 



The remainder of the British Museum specimens [J 12900, 

 J 12901, J 12902, J 12904] and one of my own [414] will be noticed 

 later as varieties. 



Xos. 413 and' 955 have the test in excellent preservation. In 

 J 12901 it is slightly decomposed and of a beautiful chalky white, 

 like so many of the fossils from the Olenellus Limestone of the Comley 

 Quarry. The other specimens have the test more or less decom- 

 posed, or actually removed. 



Cranidium : Size — rather small; length = 5 to 7 millimetres. 



General form. — Trapezoidal, widest behind; widely rounded 

 in front ; proportion of length to width = 3:4. 



General convexity. — Considerable; apparently about 4. ; with 

 features in strong relief. 



Glabella. — AYithout the occipital ring, about two-thirds of the 

 length of the head-shield; wide; very convex transversely and also- 

 longitudinally ; highest in the middle of the length ; parallel-sided, 

 with semi circularly rounded apex ; marked at the sides by three 

 pairs of furrows, of which the posterior is strongly curved Lack- 

 wards, the next is similarly directed but not so strongly, and the 

 third is only sometimes discernible. 



Occipital furrow. — Shallow and wide; entire; somewhat 

 curved backwards, and weak in the middle of its length. 



Occipital ring.— As wide as the glabella; expanded in the 

 middle to a rounded angle ; and bearing a tubercle or incipient spine 

 directed backwards. 



Axial furrow. — Wide; slightly hollowed and not marked by 

 any impressed line : not traceable round the apex of the glabella. 



Fixed cheek s. — Suggestive of spherical triangles ; flatly convex, 

 rising a very little from the axial furrow, almost flat transversely 

 to it, curving over towards a groove (deepest posteriorly) in rear of 

 the eye-lobe ; anteriorly they fall away in elevation, and merge into 

 the frontal limb beyond the ocular ridge ; posteriorly they are 

 limited by a steep curve down to the postero-lateral limb. 



Eye-lobe. — One-third the total length of the head ; the posterior 

 end, which is a little enlarged, does not quite reach the postero- 

 lateral limb ; from this point the surface of the lobe, which is- 



