412 MR. F. R. COWPER REED ON THE [Aug. 1 896, 



Again others have the abrupt posterior truncation as in /. Davisi, 

 but all the other characters of /. Bowmani. 



The amount of curvature and convexity of the head-shield is a 

 variable feature, and not of much classificatory importance. 



Illjenus Bowmani, var. longicapitatus. (PI. XX. fig. 5.) 



Head-shield parabolic to semi- oval, the hinder two-thirds of the 

 surface flattened, but the front curves down suddenly and steeply. 

 Neck-furrow plainly visible on the cheeks. Surface of the head- 

 shield minutely punctated. Eye rather more forward than in the 

 type-form. Other characters identical. 



The measurements of one specimen are given to show the pro- 

 portionate size of the different parts of the middle shield. 



millim. 



Length of shield 33'0 



Width of do. at level of eyes 41*0 



Length of glabella 15*5 



Width of do. at base 180 



Width of fixed cheek at eyes 12-0 



Note. — Some of the head-shields of 1", angustifrons, Holm, re- 

 semble in general appearance those of this variety, but the eyes 

 seem to be larger and more forward in position. 



Ill^nfs Bowmani, var. brevicapitattjs. (PI. XX. fig. 4.) 



Head-shield transversely elliptical ; length is to breadth as 2 : 3. 

 The anterior edge forms a much flattened forward curve. Glabella 

 rather shorter than the type-form. Sculpture of middle shield as 

 follows: — Close to anterior margin and parallel to it are a few 

 continuous raised thread-like lines, conveniently called ' terraced 

 lines ' by Holm, and between these and the anterior end of the 

 glabella are present in some specimens shorter scattered similar 

 lines, arranged more or less concentrically with the margin. On 

 the glabella itself there are three groups of similar lines, a median 

 group of short lines arched forward, and a pair of lateral groups of 

 slightly curved oblique lines. Across the base of the glabella are a 

 few longer horizontal straight lines. Very minute scattered puncta 

 occur over the whole surface of the head-shield. 



In all points except the above this variety agrees with the type- 

 form. 



Measurements of two Specimens. 



I. II. 



millim. millim. 



Length of head-shield 26-0 19'5 



Width of do. at level of eyes 340 240 



Distance between facial sutures where they 



cut the front margin , 29"0 220 



Length of glabella KM) 7'5 



Width of do. at base 170 105 



