REPORT OF THE DIRECTOR I9I2 I39 



The Species under present consideration conforms in these 

 structures to other American Homalonoti and is to be directly 

 compared with H.' v a n u x e m i of the New York Helderberg- 

 and H. major of the New York Oriskany, accounts of which 

 are to be found in Palaeontology of New York, volume 7. This 

 resemblance is not unexpected in view of the many other affili- 

 ations of the Perce and Grande Greve Lower Devonic faunas 

 with those of New York. The Perce Homalonotus is represented 

 by specimens which indicate its large size. The largest known 

 example of H. v a n u x e m i is a broken individual from Ron- 

 dout, N. Y., and indicates an animal 280 mm in length, which is 

 almost exactly the proportions of the Perce species. But even 

 so large, these specimens fall far below the dimensions of 

 H. major, the largest of all members of the genus. Yet there 

 are, between these two species, few differences except dimen- 

 sions, habitat and geologic horizon. In structure they are 

 closely alike, the smaller H . v a n u x e m i occurring in the 

 Helderberg limestones and lime shales and H . major in the 

 Oriskany silicious limestones. The Perce species is rather bet- 

 ter preserved and now better known in its details than either of 

 the New York species mentioned, but its designation must show 

 its affinity to them even at the cost of a multiplex name. I there- 

 fore venture so far as to express this relationship by the desig- 

 nation Homalonotus ( v.-m. ) perceensis. 



The structure of the parts is indicated in the drawings which 

 show the pygidium in normal convexity and entire, six of the 

 eleven thoracic segments (all are preserved on a second but 

 somewhat worn example), the head, partly worn away and 

 the hypostoma. The obscurity of segmentation of the pygidium 

 is characteristic and differential from other Devonic species, 

 especially the common middle Devonic H . d e k a y i . The cephalon 

 of H. V a n u X e m i - m a j o r has not been well made out and 

 the hypostoma of this type is now seen for the first time, 

 both of the Perce specimens showing this organ. 



The author has shown the presence of H . v a n u x e m i in 

 the Lower Devonic Moose River formation of Maine at Mata- 

 gamon and Moosehead lakes. ^ Until now no representative of the 

 genus has been known from points farther north. 



1 N. Y. State Mus. Mem. 9, v. 2, p. 67. 



