XXXIII. LEURESTHES 81 



130 Chirostoma estor Jordan, 1879.-^*- 



Chirostoma estor, Jordan, Proc. U. S. Nat. Mus., 2, 298, 1879 ; Steindachner, Denk. 

 Akad. Wiss. IVien, 62, 523, 1895; Jordan and Snyder, Bull. U. S. Fish 

 Comm., 19, 141 (footnote), 1899 (1900) ; Jordan and Evermann, Bull. U. S. 

 Nat. Mus., 47, pt. 3, 2839, 1898; pt. 4, 3165, 1900; Meek, Publ. Field. Mus. 

 (Zool), 3, 116, 1902; 5, 180. 1904; Regan, Biol. Centr.-Atner., Pisces, 60, 1907. 

 Lethostole estor Jordan and Evermann, Bull. U. S. Nat. Mus., 47, pt. 1, 792, 



1896. 

 Type-locality. — "Lake Chapala." (Perhaps by error. The type was sent to the 

 U. S. National Museum by Dr. Alfredo Duges of Guanajuato as "Pescado 

 Blanco de Chapala," but subsequent collectors have not found it in Lake 

 Chapala, while it abounds in Lakes Patzcuaro, Zirahuen, and Xochimilco.) 

 Atherinichthys albus Steindachner, Anz. Akad. Wiss. Wien, 31, 148, 1894. 



Chirostoma album Jordan and Snyder, Bull. U. S. Fish Comm., 19, 141 (foot- 

 note), 1899 (1900); Jordan and Evermann, Bull. U. S. Nat. Mus., 4, 3165, 

 1900. 

 Type-locality. — Lake Patzcuaro, Mexico. 

 Range. — Lakes in the Lerma Basin and the Valley of Mexico (known from Lakes 

 Patzcuaro, Zirahuen, and Xochimilco). 



This species is very similar to its congener, C. humboldtianum, 

 but may be at once distinguished by the much smaller size of its scales. 



As Dr. Meek has noted, the series from Lakes Patzcuaro, Zirahuen, 

 and Xochimilco are not wholly similar. Those from Xochimilco (like 

 some examples of C. regani and C. humboldtianum from the same 

 lake), are unusually light in color; they also have the head longer and 

 narrower than in the others. The head is usually contained about 3.3 

 times in the length without caudal in specimens from Xochimilco ; 

 3.5 times in those from Patzcuaro ; 3.7 times in those from Zirahuen. 

 But in one from Zirahuen the proportion is 3.4, as in some from Patz- 

 cuaro and Xochimilco. This difference is apparently to be regarded as 

 racial rather than specific. 



Teeth usually arranged in two or three series anteriorly, occasionally 

 forming a narrow band ; enlarged in the outer mandibular and inner 

 premaxillary series. 



XXXIII. LEURESTHES Jordan and Gilbert, 1880. 



LEURESTHES Jordan and Gilbert, Proc. U. S. Nat. Mus., 3, 29, 1880; Bull. U. S. 

 Nat. Mus., 16, 405, 1883; Jordan and Evermann, ibid., 47, pt. 1, 801, 1896. 

 Orthotype. — Atherinopsis tenuis Ayres. 

 Range. — Coasts of California and Lower California. 



131. Leuresthes tenuis (Ayres), 1860.-^'- 

 (Plate XI, Fig. 39, from Photograph by Thompson) 

 Atherinopsis tenuis Ayres, Proc. Cal. Acad. Nat. Set., 76, 1860. 



Leuresthes tenuis Jordan and Gilbert, Proc. U. S. Nat. Mus., 3, 29, 1880; 

 Bull U. S. Nat. Mus., 16, 405, 1883; Jordan and Evermann, ibid., 47, pt. 1, 

 802; Hubbs. Univ. Cal. Publ., Zool. 16, 160, 1916; Osburn and Nichols, Bull. 



