BRITISH FOSSILS. 



Decade VII. Plate V. 



CYPHASPIS MEGALOPS. 



[Genus CYPHASPIS. Bitrmeistee. (Sub-kingdom Articulata. Clasa Crustacea, 

 Order Entomostraca. Tribe Trilobitse or Palseadse.) Head tubercular, strongly mar- 

 gined ; glabella very convex, resembling half an egg, much shorter than the head, 

 without lobes, except a small basal pair which are longitudinal, oval, and deeply divided 

 from the base of the glabella (and an obscure furrow above these on each side) ; cheeks 

 very gibbous, the smooth eyes rising to a high level, without an ocular ridge ; facial 

 suture direct forwards to the margin from the eyes, and behind cutting the posterior 

 margin near the angle, which is long-spinous ; a small rostral shield present ; thorax 

 of 11 to 17 rings (or more ?), the sixth joint of the axis frequently bearing a spine ; 

 pleurae grooved ; tail small, of few rings. Kv(pos, a convexity ; ha-irls, a_^shield, in allusion 

 to the inflated carapace.] 



[Section Cyphaspis; glabella moderately large, thorax of 11 rings.] 



Diagnosis. C. parvulus ; capite undique granuloso, f route rotundato ; 

 glabella, suhhemisphericct, nec gibhd, oculos maximos vix supereminente ; 

 lohis posticis ohovatis angustis ; genis latitudine glabellam cequantibus ; 

 angulis longi-cornutis ; limbo ante glabellam declivi angusto — vix margini 

 incrassato latiori ; thorace segmento sexto armato, spind crassa appressd 

 caudce apicem attingente ; pleuris inermibus ; caudd lateribus unisulcatis. 



Stnontms. Earpes'^ megalops, M*CoY (1846), Synopsis Sil.Foss. Irel. 

 pi. 4. fig. 5. Harpidella megal., Ann. and Mag. Nat. Hist. (1849), 

 vol. iv. 412. 



"We have figured, for the first time in Britain, a complete specimen, 

 of this genus ; it has been known for some years on the continent, 

 and is one of those genera which are common to the Lower Silurian, 

 Upper Silurian, and Devonian rocks, while it does not ascend into 

 the carboniferous rocks. 



Description. — One of the smallest known species of the genus ; 

 its length is never more than half an inch : the head, which is the 

 widest part, is rather more than five sixteenths broad. The usual 

 length is not above three eighths of an inch. General form convex 

 and truly ovate, with the extremities obtuse. Head very convex and 

 strongly granulose, in form about a semicircle, but contracted at the 

 [vii. v.] 7 E 



