54 
PALEONTOLOGY OF NEW YORK. 
produced into slender spines which extend as far as the fourth or fifth thoracic seg¬ 
ment; (d) the axis of the pygidium hears ten distinct annulations, and upon the 
cast of the under surface indications of five more ; (e) the pleurae of the 
pygidium each hear ten annulations, the last of which is often indistinct; 
(f) the caudal extremity is furnished with two short, obtuse, depressed, sub- 
spiniform processes; (g) the surface of the pygidium, in well-preserved 
examples, bears a double axial row of tubercles, with a fainter row on 
either side, and scattered tubercles of the same strength over the pleurae. 
These characters appear to be persistent and indicate a well-defined specific 
variation from the type of Dalmanites selenurus. 
Distribution. The range of this species appears to be restricted to the out¬ 
crops of the Upper Helderberg limestone in the western counties of the State, 
where D. selenurus is apparently of rare occurrence, viz., Schultz’s Farm, near 
Clarence, and Williamsville, Erie county. 
Dalmanites (Odontocephalus ?) cokonatus. 
PLATE XI B, FIGS. 12-14. 
Balmania curonata, Hall. Descr. New Species of Fossils, etc., p. 58. 1861. 
Bahnania coronata. Hall. Fifteenth Kept. N. Y. State Cab. Nat. Hist., p. 86. 1862. 
Dalmanites coronatus, Hall. Illustrations of Devonian Fossils, pi. xii, tig. 17. 1876. 
A SINGLE example of this species has been observed, and this consists of the 
pygidium and a portion of the thorax, both of which are closely similar to the 
corresponding parts in Dalmanites selenurus, the pygidia of the two species having 
the same number of axial and pleural annulations. The single specimen how¬ 
ever has a caudal extremity free of spines but broadly emarginate, evenly 
rounded and bent slightly upward. There is no evidence that spines have ever 
existed and have been accidentally lost during the life of the animal, but the 
posterior margin appears to have been preserved in a normal condition. If 
this varietal feature prove, upon more complete knowledge, to be accompanied 
by a variation in the details of the head from that of D. selenurus, the species 
will afford an interesting initial form for the differences exhibited in the caudal 
spines of the several species of the sub-genus Odontocephalus. 
Distribution. Upper Helderberg group. Corniferous limestone; near Auburn, 
Cayuga county. 
