F. R. Cowper Reed — Some Wenlock Species of Lichas. 5 



perfect specimens, enable me to give a complete description of the 

 species, and render possible the identification of isolated head-shields, 

 previously of doubtful specific position. 



Diagnosis. — Head-shield broadly parabolic, more than twice as 

 broad as long, swollen centi'ally, bent down at sides and strongly in 

 front. Glabella elevated, convex, large, broader than long ; greatest 

 width across middle third. Central lobe long, subcylindrical with 

 parallel sides between anterior bicomposite lateral lobes, slightly 

 expanded in front, embracing front end of these lobes ; defined pos- 

 teriorly by strong carved transverse furrow at level of second lateral 

 furrow. Anterior lateral lobes rather swollen, oval but slightly 

 pointed behind ; each as broad as central lobe ; extend three-fourths 

 the length of the glabella ; are defined externally by strong furrow. 

 Middle and basal lobes obsolete, their place being occupied by a sub- 

 triangular, uniformly swollen surface, not differentiated or marked 

 off from the fixed cheek, except behind the eye, where the posterior 

 portion of the axal furrow is faintly developed. 



Between the central lobe and neck-ring is a narrow post-central 

 lobe depressed below the level of the central and lateral lobes, and 

 defined laterally by the weak backward continuation of the first 

 lateral furrows to the neck-ring ; three conspicuous large isolated 

 tubercles usually ornament it. 



First lateral furrows curve inwards strongly from anterior point 

 of origin, sweeping round front end of anterior lateral lobes ; then 

 run backwards to transverse furrow with increasing strength and 

 almost parallel to each other, behind which they diverge and are 

 feebly continued to neck-ring. 



Axal furrows strong, curved outwards, defining outer border of 

 anterior lateral lobes ; not continued behind second lateral furrows, 

 which at level of eyes pass imperceptibly into them. Close to 

 the neck-ring a faint furrow on each side represents the posterior 

 portion of the axal furrows. 



Second lateral furrows form a continuation inwards of the axal 

 furrows round the base of the anterior lateral lobes, joining first 

 lateral furrows at angle of 75°-90°. Transverse central furrow 

 runs across middle of glabella as continuation of second lateral 

 furrows with equal strength, but with independent backward curva- 

 ture. Occipital ring arched forwards, swollen, broadest in middle, 

 generally with median tubercle. 



Fixed cheeks triangular, swollen towards inner portion, not 

 marked off in middle from glabella ; posterior edge straight, hori- 

 zontal at right angles to axis of glabella, but bending sharply forward 

 at outer angle at about 130°. Eye-lobe moderate, prominent, 

 horizontal, at level of second lateral furrow. Neck-ring on posterior 

 margin elevated, narrow, ornamented with single row of large 

 tubercles. 



Facial suture makes a sharp bend outwards behind eye, curving 

 thence backwards to cut lateral margin behind spine. 



Free cheek narrow, elongated, triangular, inner portion swollen, 

 bearing prominent elevated eye of moderate size. Middle of lateral 



