Report of the State Geologist. 107 



anterior arc as in Odontocephalus. The eye-lobes are high, the eyes 

 themselves large and elevated. The anterior lobe of the glabella is 

 low, somewhat pentagonal in outline and its definition from the ante- 

 rior border unusually indistinct. As in most of the Dalmanites of 

 this fauna the lateral members of the first and second pair of lobes 

 are coalesced not only with each other but to a very considerable 

 degree with the eye-lobes. The lateral extensions of the facial suture 

 lie in deep grooves in their passage over the cheeks. The thorax 

 presents no additional features of importance, except that the 

 segments are considerably produced at their lateral extremities, and 

 terminate in sharp points, without showing well-defined articulating 

 faces. 



In this specimen, however, the marginal spines of the pygidium are 

 remarkably short, while usually in the New York specimens they are 

 larger than in those from the Cornif erous limestone of Ohio. The term- 

 inal spines, also, are relatively quite broad and stout and bear on their 

 outer margins three spinules. As far as can be ascertained there is 

 no evidence of erect spines on the crescentic border as in the allied 

 species Goronura myrmecophorus, Geeen, but the structure of the 

 posterior crescent shows how closely this form approximates the 

 latter species. 



The structure of Mr. Conead's species, Asaphus aspectans (which is 

 now to be referred to the genus Goronura, proposed in Volume YII of 

 the Palaeontology of New York), is established, and it has probably 

 never before happened in the history of discussions upon the trilo- 

 bites that a species at once so imposing in its proportions and so 

 characteristic of its founa, has been virtually reconstructed from 

 so insignificant a fragrant, with a meager and imperfect description 

 of that. 



We believe, however, that Conead's term must yield to an earlier 

 one of Dr. Green's, Asaphus diurus, a name which has never been 

 accepted, from certain imperfections in the original description. This 

 species was proposed in the American Journal of Science and Arts, 

 1839 (vol. xxxvii. No. 1, p. 40, July), under the title " Description of 

 a New Trilobite." In order to apprehend its value, the essential 

 portion of the description is reproduced: ^ 



"Clypeo? costis striatis, tuberculatio; cauda bipartita; corpore 

 depresso. 



" The fragments of this Asaph which I have examined, consist of 

 nineteen articulations of the abdomen and tail. The costal arches of 

 the lateral lobes are very peculiar. They are marked by a shallow groove, 

 or impressed line on their upper surface, studded on each side with quite a 



