MAY, 1902. THE ICHTHYOLOGY OF MEXICO MEEK. 109 



species, all with scales having the edges more or less crenate. This 

 group would comprise two species of small size (grandoculc and 

 chapalce], one of medium size (promelas) and three species of large size. 

 Scales 49 to 70; gill-rakers 24 to 27. Vertebrae 43 or 44. The firm- 

 ness of the flesh and the opaque color cannot be correlated with any 

 other character. If divided on this basis, arge, humboldianum (except 

 from Patzcuaro) and estor from Xochomilcho and Zirahuen, would 

 be included. In the key I have placed all small species with large 

 scales, fewer than 45 in the lateral series, in one division (Eslopsaruni). 

 All other species with scales having entire edges {Chirostoma}, in a 

 second, and all species with scales having crenate edges (Lethostole), 

 in a third. 



The species of this genus are very variable, and are perhaps not 

 yet well differentiated. The environment of the species of this genus 

 is very diverse; some species are found in clear running water, others 

 in lakes like Chapala, which has several inlets and a large outlet, 

 while many of the species are in lakes which have no outlet, of which 

 Patzcuaro, Zirahuen and the lakes in the Valley of Mexico are good 

 examples. Some of these lakes are quite fresh; others, as Quitzeo 

 and Patzcuaro, are quite brackish. So far as I could learn Quitzeo is 

 the most brackish of all, and Patzcuaro probably next; and in these 

 two lakes the fishes were much lighter in color than those from other 

 places. The darkest colored fishes were taken from Lago de Chalco 

 and Lago de Zirahuen. 



The alimentary canal of Chirostoma is shorter than the total 

 length of the body. The peritoneum is black. A few stomachs 

 examined indicate the food to be insect larvae and insects. In one 

 specimen of C. estor the stomach contained a partly digested 

 Chirostoma. I was told that these fishes will not take a hook. 

 The larger species are excellent eating, the flesh being firm and 

 white when cooked and not full of small bones. The smaller species 

 and the young of the larger ones, together with all of the species of 

 Peeciliida are dried in large quantities by the Indians and are thus ship- 

 ped to neighboring towns, or are kept for future use. All of the fishes 

 caught in the larger fresh waters of Mexico are eaten none being 

 thrown aside as of no value. 



At Patzcuaro, Zirahuen, Chapala and Quitzeo the fishes are 

 caught in long seines. These seines have coarse mesh near the end, 

 which becomes gradually smaller unttf the large bag in the middle 

 has about \ inch mesh. The shore of the lake is often not suitable 

 for drawing the net. It is thrown out in the usual way, drawn by 

 ropes from the shore until the ends of the net are near each other. 



