﻿-"30 ME. E. S. COBBOLD ON THILOBITES FROM: fFeb. I9IO, 



.MlCMACCA (?) PAEVULA, Sp. 110T. (PI. Ill, figS. 9 & 10.) 



One imperfect internal cast of the cranidium [412] and one 

 fragment with the test preserved [-111], and showing the glabella 

 and fixed cheek, form the only material at present available tor 

 .description. 



Ceaniditjm : Size — minute; 2 to 2| millimetres long. 



General form. — Subquadrangular, with rounded front. 



General convexity. — Rather flat; curving down somewhat 

 at the front, and perhaps at the sides. 



Glabella. — Moderately convex'; touching the front margin; 

 widening forwards beyond the ocular ridge ; with four pairs of 

 incomplete furrows, which are slightly impressed at the sides and 

 very evenly distributed in the length. 



Occipital furrow. — Wide and shallow ; traceable all across. 



Occipital ring. — Narrower than the glabella, and produced 

 backwards to a point or short spine. ' 



Axial furrow. — Wide and very slightly impressed; increasing 

 in strength forward of the ocular ridge. 



• Fixed cheeks. — Subquadrangular; as wide as the glabella 

 . and nearly flat ; falling a little to a hollow behind the eye-lobe; 

 limited anteriorly by the ocular ridge, and posteriorly by a steep 

 descent to the postero-lateral groove. 



Ocular ridge. — Arising from the outer side of the axial 

 furrow a little posterior to the anterior glabellar furrow ; passing 

 outwards at right angles to the glabella to join the eye-lobe by a 

 bold curve. 



Eye-lobe. — Fully half the length of the head; rising rather 

 steeply from the depressed edge of the fixed cheek ; reaching back- 

 wards nearly to the posterior marginal groove. 



Postero-lateral limb. — A groove margined by a slightly 

 raised and rounded ridge, which is geniculated almost as far out as 

 the eye-lobe. 



Frontal limb. — Not wholly known ; apparently it consists of 

 a narrow upturned fillet touching the glabella, and separated from 

 it by a distinctly impressed line. This fillet is produced on each 

 side to form the anterior curve of the shield ; between this and 

 the ocular ridge there seems to be a comparatively wide fiat area. 



Facial suture. — Anterior branch unknown; posterior branch 

 apparently short and direct to the posterior margin immediately 

 behind the eye-lobe. 



Test. — Very finely granular. 



This little species differs from Mr. G. F. Matthew's type for the 

 genus (M. mattlieivi) in its minute size; and, but for the width 

 of the glabella, it might well be a larval form of this genus. The 

 long and distant eye-lobe and the glabella reaching the front margin 

 are both {fide Matthew) 1 embryonic features in allied genera. 



Locality and horizon. — Comley, from the Olenellus Lime- 

 stone of the quarry, and of the excavation 200 yards south thereof. 

 1 Trans. Eoy. Soc. Can. vol. v, sect, iv (1887) pp. V2'6 ct segg. 



