FISHES, LAHONTAN SYSTEM OF NEVADA AND NORTHEASTERN CALIFORNIA. 59 



Head 3.75 in length to base of caudal; depth 3.75; depth caudal peduncle 10; snout 3.5 in head; 

 eye 4.5; interorbital space 3; height dorsal 1.4; anal 1.7; length pectoral 1.3; ventral 1.7; caudal i; 

 scales lateral series 53; dorsal rays 8; anal 8. 



The general shape is much like that of the young of S. obesus, the head being longer and more 

 pointed, the mouth a little less oblique, the eye slightly larger, the opercle more angular, and the 

 caudal peduncle more slender. Width of body somewhat less than half the depth. Diameter of eye 

 less than length of snout; interorbital space convex; cleft of mouth not quite reaching a vertical through 

 anterior edge of orbit. Gillrakers 13, slender, sharply pointed and curved downward; the largest 

 about equal in length to vertical width of posterior nostril ; space between gillrakers about equal to 

 width of base of gillraker. Teeth i, 5-5, i; hooked, with a narrow grinding surface; the teeth of inner 

 row very frail. Lateral line complete, strongly decurved on anterior third of body. Body completely 

 covered with large scales, which are nowhere much reduced in size nor crowded. Dorsal inserted 

 well behind a vertical through origin of ventrals; edge of anal straight; caudal deeply cleft, the lobes 

 pointed ; edges of ventrals rounded, the depressed fin just reaching the anal opening ; pectorals obtusely 

 pointed. 



Color in spirits dark above and light below, as usual in minnows, the dusky pigment spots clus- 

 tering along the edges of the scales. A rather indefinite lateral stripe extends along the side, becoming 

 more definite posteriorly, where it is about 3 scales wide, and ending just anterior to base of caudal 

 fin in an enlarged, rounded spot. In life the upper parts were olive, the sides somewhat silvery. The 

 peritoneum is silvery but thickly dusted with black pigment. The alimentary canal is not quite 

 equal in length to the total length of the specimen. 



The teeth of the inner row are very frail and seem to be on the verge of disappearing entirely. 

 Three specimens, in addition to the type, have them as follows: i, 5-5, i; i, 4-5,0; o, 5-5, i. 



Only four examples of this species have been seen. They were taken with baited hook from below 

 the wharf at Tahoe City. All were females, the eggs being well developed and relatively few in num- 

 ber. Measurements of these specimens follow: 



Measurements op Richardsonius microdon. 



Length of body mm 



Length head 



Depth body 



Depth caudal pedimcle 



Length caudal peduncle 



Length snout 



Diameter eye 



Interorbital width 



Depth head 



Snout to occiput 



Snout to dorsal 



Snout to ventral 



Length base of dorsal 



Length base of anal 



Length of body mm. . 



Height dorsal 



Height anal 



Length pectoral 



Length ventral 



Length caudal 



Dorsal rays 



Anal rays 



Scales lateral line 



Scales above lateral line 



Scales below lateral line 



Scales before dorsal 



o- 19 



• 17 



•IS 

 .26 



8 



56 



6 

 38 



The writer is inclined to regard this species as a possible representative of R. caurinuso- of the Co- 

 lumbia. They are not very unlike in general appearance, although the Columbia species is more slen- 

 der, suggesting Ptychocheilus in shape. The dorsal fin in each is inserted posterior to a vertical through 

 bases of ventrals. Its relationships may be with R. bicolor of the Klamath. It is probably not closely 

 related to R. atrarius^ of the Bonneville Basin. 



a A specimen of Richardsonius caurinus was lately foimd by the writer in the National Museum collection. It is the second 

 recorded since the species was described by Richardson. It was collected by Livingston Stone, but nothing further is known 

 of it. It measures9M inches in length. There are 79 scales in the lateral line, about 20 between lateral line and back. Dorsal 10; 

 anal 9. The pectorals are rather sharply pointed. The edge of the anal is slightly concave. 



6 It is beUeved that the name Richardsonius atrarius (Girard) should stand for the species recognized by recent authors as 

 Leuciscus lines^s (Girard). (Bull., No. 47. United States National Museum, 1896, p. 232.) The type of Tigoma lineaia 

 Girard is lost, and the locaUty from which it was obtained is unknown. Furthermore, it was described (Proceedings, Academy 

 Natural Sciences. Philadelphia, 1856. p. 206.) as being "elongated, the body subfusiform, the head small and conical." aform 

 apparently Uke that of R. balUalus, R. kydrophlox, or R. egregius. Also, the describer remarks of his Tigoma egregia, "By its 

 general aspect this species resembles T. lineaia." Siboma atraria Girard (Proceedings, Academy Natural Sciences, Philadelphia; 

 1856. p. 208) on the other hand is a deep-bodied, thick-tailed form with a comparatively large head, not to be compaied with 

 R. cgregius {Tigoma egregia), which is elongated, subfusiform, trim, and graceful. 



The type of 5. atraria. United States National Museum, no. 236. is a specimen somewhat over 6 inches long. There are 

 9 rays in the dorsal fin, 8 in the anal; 56 scales in the lateral series; 12 between lateral line and back; 30 between occiput and 



