RAYMOND: somi. \i.\\ ORDOVICIAM TBIL0BITE8. U1)f> 



En< him kid\i. Angelin. 

 Ectenonotus, gen. uov. 



Among the anomalous trilobites described by Billings was one which 

 had a glabella very like that of a Pliomerops, and a pygidium strongly 

 suggestive of Encrinurus. Although do entire specimens have been 

 reported the "glabella and pygidium were found in about equal 

 numbers together, and in great abundance. Out of one small piece 

 of rock scarcely a yard in length, there were taken twenty-seven speci- 

 mens of the glabella, and twenty-four of the pygidium. In this mass 

 of rock there was no other head to which the pygidium could be 

 referred, nor any other pygidium to which the head could possibly 

 have belonged." 



The pygidium is distinctly Kncrinurus-like in its elongate narrow 

 form, very long axial lobe with numerous rings, and particularly 

 in the way in which the posterior ribs on the pleural lobes curve back 

 around the end of the axial lobe. The pygidium shows some differ- 

 ences from both Encrinurus and Cybele, but they are of a relatively 

 minor character, and if it were not for the associated cranidium, 

 the species would undoubtedly be admitted to the genus Encrinurus. 



AVhile the cephalon is Pliomerops-like, certain Encrinurid char- 

 acteristics may be seen in it, particularly when compared with Cybele. 

 The form of the glabella and position of the glabellar furrows is similar 

 to what is seen in Cybele bellatula (Dalman) (Schmidt, Mem. Acad, 

 imp. sci. St. Petersburg, 1881, ser. 7, 30, p. 203, pi. 13, fig. 9) and the 

 glabella does not expand toward the front as in Pliomerops. The 

 most important point, however, is that the eye is not situated close 

 to the glabella as in Pliomerops. The eye is not shown in any of the 

 specimens but enough of the fixed cheek is preserved to indicate that, 

 whether the eye is ultimately found to be far forward, as in Encrinu- 

 rus and some species of Cybele, or far back as in other species of that 

 genus, it must at least be placed at some distance from the glabella 

 and thus be p]ncrinurid in position. 



Billings made the cranidium the holotype of the species Amphion 

 instoii i, so that in case it should prove that the cranidium and pygi- 

 dium do not belong together, the pygidium will belong to an unnamed 

 species. I propose to designate the specimen from Newfoundland 

 retaining the thorax and pygidium as the holotype of the genus, in 

 order that there may be in the future no uncertainty as to how the 

 names should apply. 



