660 SILURIAX TRILOBITES OF NEW SOUTH WALES, V., 



that, under this name, De Koninck figured cephalons of two dis- 

 tinct species. To which of these is the name of C . Tmirchisoni to 

 be restricted in the first place? To the Quedong example most 

 certainly I because it is that one "(jui a servi a ma description," 

 and because it accords with the description in having a glabella 

 "in the form of a club," and four transverse non-interrupted 

 gi'ooves, which are not grooves at all, but merely intei-spaces 

 between lines of granules. Therefore, the name C ramus niurchi- 

 mul should be restricted to De Koninck's PI. i., fig. 9. Now, 

 whether or no this restricted cephalon is identical with that of 

 Foerste's E. niitchelli is very diliicult to say, but we have a lurk- 

 ing suspicion that it may be, on account of a pyriform glabella 

 and transverse lines of granules at its base parallel with the 

 neck-ring and furrow in both; in some young specimens this is 

 very marked indeed, and we figure one such. But against this, 

 is the apparent absence of the large axial tubercles in De 

 Koninck's figui'e, and the very diU'erently situated eyes; this 

 absence of the lai-ge axial tubei-cles in the illustration referred to 

 was also noticed by Mr. Foerste. There also occurs here one of 

 those little errors which we are all liable to, for although Prof. 

 De Koninck said "la joue mobile et Tangle genal me sont in- 

 connus," the free cheeks are shown in his fig. 9. 



By what name is this trilobite to be known? In consideration 

 of the doubts raised in the preceding paragraphs, it appears to 

 us that Foerste's name must be recognised. Any claim to 

 recognition of De Koninck's appellation would seem to be in a 

 great measui'e nullified by the inclusion under it of more than 

 one form, but had it been possible to show that Ci-omns mur- 

 chisoni and Encrinums mitchelli were one and the same, then 

 certainly the former would have precedence. 



In the numerous specimens of E. mitchelli examined by us, 

 there appears to be no definite proportion between the axial 

 length of the glabella and thorax, as the following proportions 

 will show— 6:10, 8:11, 9:11, 5:9, etc. The eciuality between 

 the anteroposterior length of the glabella and the distance be- 

 tween the eye-lobes is very constant. In some specimens, the 



