534 W. B. R. King — Notes on fJie Genus Sphmrocoryplie. 



rising blunt triangular raised central portion possessing two marked 

 knobs, rather below the centre. The anterior part is nearly flat, 

 with only slight undulations. The general outline of the whole 

 would be triangular. 



It is difficult to find any family with a similar type of hypostome ; 

 certain it is that it is far from the Cheirurid type, but it must also 

 be admitted that very little resemblance can be seen between it 

 and the normal Encrinurid tyjoe, with its peculiar and striking 

 central tongue-like anterior protrusion. 



A study of the hypostome of Staurocephalus therefore confirms 

 the view that it should be removed from the Cheiruridse, but does 

 not seem to indicate that it should be put into the Encrinuridee 

 unless it branched off from some very early form before the 

 characteristic frontal tongue was developed. However, all figures 

 of Encrinurus or Cybele which show the hypostome have this tongue 

 well develoj^ed. If, how^ever, Staurocephalus is barred from both 

 the Cheiruridse and Encrinuridee it is difficult to find a family in 

 which to place it. 



It may not be out of place here to study some points in connexion 

 with the general structure of Sphcerocoryphe and forms of similar 

 general appearance. As the specimen from Norber Brow, although 

 much compressed laterally, shows all the details of the ornamentation 

 clearly, it was decided to draw a restoration, taking the details 

 largely from the Norber Brow specimen, but the general outline 

 from some of the Girvan sj^ecimens, especially from a nearly com- 

 plete specimen in the British Museum (No. I. 16047). 



The restoration (Plate XIII) is intended to bring out some of the 

 more striking features of SpihcBfocoryp)he thomsoni Reed. A detailed 

 description of the sjjecies is given by Dr. Reed in his Girvan Trilobites 

 monograph.^ To this there is nothing to add, but a point which 

 occurs to a worker on Lower Palaeozoic Trilobites, is that when 

 identifying specimens of this sjoecies it should be borne in mind 

 that the usual type of pygidium is that shown in the restoration, ^ with 

 apparently one short and one long spine on each side of the axis. 



From the foregoing notes there would seem to be little real 

 similarity between Sphcerocoryjohe and Staurocephalus ; the only 

 cause of the confusion which arose between these two genera was the 

 marked swelling of the frontal part of the glabella. This swelling 

 is present in several other genera, particularly Deiphon, probably 

 a direct descendant of Sphcerocorj/phe, and also in the peculiar 

 Australian genus Onycopyge described by Dr. H. Woodward.^ 

 Even some species of Phacops (s.s.), for instance P. cepJialotes Corda 

 fromEtageG.of Bohemia, show considerable swelling of the frontal 

 parts of the glabella. The origin and use of this peculiar line of 

 development seems to be rather obscure, but the subject is touched 

 upon by Dr. L. Dollo ^ in regard to DeipJion, where he attributes the 

 extremely modified form to external influences connected with its 

 mode of life. 



N.B. — For footnotes see p. 538. 



