RAYMOND: ISOTELUS GIGAS DEKAY. 261 



segments together measure 112 mm. in length. If this specimen had 

 the same proportions as the one from Toronto, it would, when com- 

 plete, have been 384 mm. long, and 260 mm. wide at the genal angles, 

 thus giving a very large surface area. 



Basilicus barr.\ndi (Hall). 

 Plate 1, fig. 4, 5; Plate 2, fig. 1, 7. 



Asaphus barrandi Hall, Foster and Whitney Rept. Lake Huperior land dist., 

 1851, pt. 2, p. 210, pi. 27, fig. 1, a-d; pi. 28. Geol. Wise, 1862, 1, p. 41, 

 fig. 4. 



Asaphus romingeri Walcott, 28th ann. rept. N. Y. state mus., 1879, p. 78. 



Asaphus wisconsensis Walcott, Ibid., p. 79. 



Plychopyge ulrichi Clarke, Pal. Minn., 1897, 3, pt. 2, p. 709, figs. 12, 13. 



Basilicus romingeri Raymond and Narraway, Ann. Carnegie mus., 1910, 7, 

 p. 49, pi. 15, fig. 9, 10; pi. 16, fig. 1^. 



When Raymond and Narraway wrote, they did not have access to 

 the Foster and Whitney report, or they would probably have adopted 

 Hall's name for this rather common Black River Basilicus. In view 

 of the remarkable resemblance of the young of Isotelus gigas to the 

 adult of this Basilicus, it deserves to be more adequately figured than 

 it has been hitherto. The species seems to be of wide geographic and 

 narrow vertical range, and should be better known than it is. 



Hall's types of Asaphus barrandi consisted of an entire specimen with 

 the cephalon mutilated and showing the hypostoma in place, two 

 imperfect pygidia, a free cheek, and a good pygidium. These speci- 

 mens are preserved in the American museum of natural history, 

 where I have had the opportunity to study them, through the courtesy 

 of Dr. E. O. Hovey, Curator of Geology. Four of the specimens, 

 (Hall, Loc. cit., pi. 27, fig. lb, c, d, and pi. 28), including the entire 

 specimen, are from Platteville, Wisconsin, and one, (pi. 27, fig. la), 

 is from St. Joseph Island, Ontario. Platteville may, then, be con- 

 sidered the type locality for the species. 



Asaphus romingeri and .4. wisconsensis were described by Walcott 

 without illustration, but are represented by a considerable number of 

 fragmentary specimens in the Walcott collection of the M. C. Z. 

 Two imperfect cranidia from the Black River at Russia, Herkimer 

 county, N. Y., have attached to them original labels indicating that 

 they are the types of the two species. These labels have, however, 



