108 Forty-fourth Report on the State Museum. 



regular row of head-like granulations. On each division of the vertebral 

 column, there is but a single row of pustulations. The lunate caudal end is 

 more expanded than in the cognate species, the A. Selenurus, and the 

 concave side of the crescent is more regularly rounded ; the whole animal is 

 much more depressed than that species, and the lateral lobes are much wider 

 in proportion to the middle lobe of the back. 



" There are two specimens of this fine species in the cabinet of 

 William Wagner, Esq., of Philadelphia, both of which were found in 

 Green county, Ohio, in the neighborhood of Xenia. The largest which 

 measures two inches long and two and a half inches wide, is a plaster 

 cast from a weather-beaten natural mould; the other occurs in a grey, 

 sparry argillaceous limestone rock. It is perhaps worthy of remark, 

 that all the specimens of the Asaph with a lunate tail, which I have 

 noticed, were natural moulds, made by the animal in the rock, the 

 shell or body having disappeared." 



This description was unaccompanied by any illustrations; that 

 portion, however, that we have underlined is a cogent delineation of 

 the characters of the pygidium of Dalmanites aspectans. The fossil is 

 hardly to be mistaken. There are but three species of crescent-tailed 

 trilobites, of the size here indicated, that are now known; Asaphus or 

 Odontocephalus selenurus, Asaphus or Dalmanites myrmecophorus and 

 Asaphus or Dalmanites aspectans. Of these Dr. Gkeen had himself 

 described two, though the first is usually referred to Eaton, who pub- 

 lished it in the same year. They are all members of the same (Cornif- 

 erous) fauna. In Miller's Catalogue of the American Palaeozoic Fossils, 

 the species is referred to the age of the Niagara; Captain Vogdes in his 

 Bibliography considers it of the age of the Hudson river group, but 

 in neither these nor any other American palaeozoic fauna, except the 

 Corniferous, is there any trilobite which even remotely suggests the 

 above description. 



The nineteen articulations of the axis of the pygidium, which per- 

 haps from its unusual size the author considered as " abdomen and 

 tail," the grooving of each pleura by a fine impressed line, on each 

 side of which is a regular row of granules, the form of the posterior 

 crescent and the relative proportions of the axis and lateral lobes are 

 all apparent in the figures given in the Palaeontology of New York, 

 Vol. VII, and in that accompanying this paper. In the hope of finding 

 Dr. Green's original specimens, search has been made in the collec- 

 tions of the Wagner Free Institute of Science, at Philadelphia, by the 

 favor of its secretary, Mr. Charles W. Johnson, but the specimens, if 

 extant, are for the time being lost sight of. 



