9G8 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
Page 156. Professor Hay (Proc. U. S. Nat. Mus. 1882) distinguishes 
Hijhognathus argyritis from the less common II. nuchalis by the follow- 
ing characters: 
«. Eye small, shorter than snout; mouth small, horizontal, the lower jaw short aud 
iucliKlcd; suborbitals broad, the anterior suborbital twice as long as wide; intes- 
tinal canal 7 to 10 times length of body Nuchalis. 
««. Eye large, longer than snout; mouth small, oblique, the jaws equal; suborbitals 
very narrow, the anterior thrice as long as broad; intestinal canal 4^ to 7^ times 
length of body Argykitjs. 
Page 160. After HyhorhyncJms svpercUiosus add: 
§0 (6).— TIISOD©^ Hay. 
(Hay, Proc. U. S. Nat. Mus. 1882: type Tirodon amnigenus Hay.) 
Pharyngeal teeth 2, 4-4, 2, compressed, not hooked, aud with a broad 
grinding surface; lower pharnygeal boues broad, sharply curved. 
Otherwise as in HyhogvMthus. (ret/na, to wear away; ddooc, tooth.) 
194 (&). T. a.MiBniig'eBaus Hay. 
Yellowish green, silvery below ; upper parts dotted with black; these 
dots forming posteriorly a dark streak along lateral line, and one along 
each side of anal; lius pale. Form and a|)pearauce of Ilybognathus 
argyritis. Jaws thin, the lower slightly included; mouth small, rather 
oblique, the maxillary not reaching front of eye; eye 3 in head, equal to 
snout. Lateral line decurved, complete. Dorsal inserted slightly before 
ventrals, a little nearer base of caudal than snout; anal small. Head 3^; 
D. 8; A. 7; scales 5-38-3. Teeth 2, 4-4, 2, formed as in Hybogruithus. 
Intestinal canal 3J times length of body. L. inches. Pearl River, 
IMississippi. {Hay.) 
(Hay, Proc. U. S. Nat. Mus. 1882.) 
Page 261. Under Hops saurus the gular plate is about 3 times as 
long as broad. 
Page 296. In Hyphaloiiednis chalybeius the interorbital width is one- 
fourth the eye, not “4 times.” 
Page 297. Coregonns coiiesi is identical with Coregonus williamsonij 
aud may be suppressed. 
Page 318. Salvelinus narcsi seems to be indistinguishable from Salve- 
linns oquassa. It may therefore, be erased. 
