TI:II.I>UITKS. 757 



in the former, investigated the nature of the hypostoma of both 

 ami found therein differences so notable that he introduced the name llnrfiina for 

 the early Silurian species; a terra which we retain as probably applicable to all our 



American 



ami Utfaliljf Knun the mlilill.- |K>rVl'm of the Galena HUU-NHI.', lladi-r, Minnesota. 

 Mr. K. <>. Urlch. 



1 1. \KI-IWA, cf. H. OTTAWKNsis Hillings (sp.). 



Among the material obtained from Dr. Robbing is a large horseshoe-shaped 

 impression of the exterior of the submarginal doublure of the head-shield. It is 

 quite Hat and its ornament apparently consisted of a great number of fine puncto 

 of about equal si/e except along the inner margin where they are larger and 

 continent in radial lines, forming a series of short divergent furrows. The marginal 



:' ll.irpina, ct. H. oltatcfntit Billings. 



outline of the shield is quite similar to that of //. vltaicensi* Hillings,* of the Trenton 

 limestone of the city of Ottawa. Indeed, the specimen conforms almost exactly in 

 size and curvature with the original figure of that species. We have above observed 

 that species with a concave cephalon may have a perfectly flat doublure, and I am 

 to believe that this specimen probably represents an individual of //. 

 is, with which it presents an additional point of agreement in the character 

 of the surface puuctte. 



formation and locality. Galena Illusion.', Wykoff, Minnesota. 



HAKI-INA BUTRBLLUM, n. sp. 



An hitherto undescribed species is represented by a head-shield with the 

 following characters: Size moderately small, outline subsemicircular. Surface 

 convex, somewhat depressed above; marginal border not so broad as in //. min> 

 tensis; deeply concave. Margin thickened, smooth and slightly upturned. Genal 

 extremities not retained. Olabella subconical, extending more than one-half the 



FtUmiolo ItoMlta. ol. 1. p IB. (. 110. UK. 



