Raymond : Noies on Ordovician Trii.obhes. 39 



section Tlie p\-gi(liuni is ncarl>- smooth, the axial lobe being only faintly 

 defined, and nearly all traces of segmentation lost. 



Beside the type species, the genus as restricted will include Asaphellus 

 homfrayi Matthew var. from the Tremadoc of Cape Breton, and the two 

 new species here described. 



Asaphellus gyracanthus sp. nov. 

 Plate XIV. figures 5-7. 



Asaphus canalis? Cleland, Bulletin American Paleontology, III, 1900. 128, pi. 



16. figs. 7. 8. — Cleland, Bulletin American Paleontology. IV, 1903. 38. 

 Isolelus canalis Weller, Paleontology New Jersey. III. 1902, p. 132, pi. 5, figs. 



5. 6. 



This asaphid is very abundant in the Beekmantown at Fort Hunter, 

 New York, but no complete specimens have been found. From the gen- 

 eral shape of the pygidia and free cheeks Cleland concluded that the 

 trilobite was probably Asaphus canalis, but the discovery of an unforked 

 hypostoma of the Asaphellus type associated with the specimens shows 

 that it belongs to another section of the family. 



Only one fairly complete cranidium, that mentioned by Cleland, seems 

 to have been found. Through the kindness of Professor Harris I have 

 been able to see this specimen. There are hardly any traces of dorsal 

 furrows, so that the glabella is as flat as in Isotelus. In front of the 

 glabella is a narrow depressed border. While there are no entire cephala 

 known, the shape of the anterior end of the cranidium is such as to indicate 

 that the facial sutures met in a point on the margin and that the whole 

 course of the suture is on the dorsal surface. The eyes are not so far 

 forward as in Hemigyraspis coUieana and are closer together. Between 

 them is a minute pustule. The free cheeks are broad, flat and bear long 

 spines at the genal angles. The pygidium is semicircular in outline, evenly 

 convex with a narrow depressed border. The axial lobe is not promi- 

 nent, but there are traces of three or four rings at the anterior end. 

 The hypostoma, of which there is a single specimen in the Carnegie 

 Museum, is similar to that of Hemigyraspis coUieana. a figure of which 

 is given on the plate. 



The [jygidium of this species differs from that of Isofeloides whitfieldi 

 in having the axial lobe much less clearly outlined and in being shorter 

 in proportion to the width, as well as in the general contour, the whole 

 surface being evenly convex in the specimens of Asaphellus gyracanthus, 

 while in Isoteloides whitfieldi the axial and pleural lobes are prominent. 



