470 CALIFORNIA ACADEMY OF SCIENCES. 98 



long and spear-shaped, very much more slender in pro- 

 portion to its length, not hollow and not receiving any of 

 the air bladder. This structure is seen in Gerres cinereus 

 (Walbaum) , in Gerres feruvianus Cuvier & Valenciennes, 

 and in Gerres lineatus Humboldt, as also in several West 

 Indian species. 



Eucinostomus californiensis is generally common along 

 the west coast of Mexico, from Guaymas to Panama. 

 It is probably, however, not found in the West Indies, 

 the closely related Eucinostomus harengulus being appar- 

 ently a different species. The specimens called califor- 

 niensis by Gill, having the premaxillary groove semi- oval 

 or f] -shaped, seem to represent the adult of this species. 

 Those called gracilis, with the premaxillary groove linear, 

 are the young or half- grown. Still others, especially 

 adults, have the premaxillary groove round, forming a pit, 

 and every intermediate character may be found. 



At first we thought it possible to separate californiensis 

 and gracilis as distinct species. The careful re-examina- 

 tion of some 200 specimens leaves us wholly unable to 

 separate them, as all grades of variation occur. Appar- 

 ently the premaxillary groove is linear in the young, grow- 

 ing broader with age, but the changes very irregular. 

 The name Eucinostomus californiensis has priority over 

 E . gracilis. 



Note. — The genus Gerres was established by Cuvier 

 in the second edition of the Regne x\nimal, the name 

 being based on seven species as enumerated by him, 

 r/10 in hens, oycna, aft r ion, ftoieti, lineatus, argyrcus and 

 flainentosns. One of these species must, therefore, be 

 chosen as the type of Gerres. In 1842, Ranzani estab- 

 lished the genus Diapterus on auratus, a species closely 

 related to rhombcus, or rather to the allied olisthostoma. In 

 1850, the name Catoclncnian was proposed by Cantor as 



