CHARACTERS OF THE ORDER HAPLOMI. 255 



in which the scapular arches are " connected with and impinge 

 on the occiput behind and on each other, and are otherwise free 

 from the cranium." In his original definition he calls Iniomi a 

 group, and later in his " Families and Subfamilies of Fishes " l he 

 treats it as a superfamily. Jordan and Evermann in " Fishes 

 of North and Middle America" raise it to ordinal rank, and 

 point out that the absence of the mesocoracoid is the most im- 

 portant character by which the Iniomi are separated from the 

 Isospondyli. 



A readjustment of the orders Haplomi and Iniomi will be 

 necessary, and either a separation based on characters unstudied 

 and unconsidered, or a merging of one into the other will result. 

 This will necessitate a study of many more forms than are here 

 considered. 



The knowledge of the following characters I obtained in study- 

 ing the relationships of Da//ia pectoralis. As I am not at this 

 time ready to take up an extensive investigation of the orders 

 Haplomi and Iniomi it seems better, while it is fresh in my mind, 

 to publish this material in the following form as a working basis, 

 rather than to hold it indefinitely in abeyance. 



Order HAPLOMI. 



Soft rayed fishes without a mesocoracoid and with the anterior 

 vertebrae normal. Parietals separated by the supraoccipital. 

 Alisphenoids not meeting in a median line in front of brain case. 

 Exoccipitals separated by basioccipital. Postclavicle composed 

 of a single element. Actinosts four. Opercular bones all pres- 

 ent. Ventral fins abdominal, each attached to a simple flat pel- 

 vic bone. Pectoral fins placed low. Dorsal fin placed more or 

 less posteriorly. Air bladder with a distinct pneumatic duct. 



Superfamily Esocoidea. 



Ethmoid represented by paired elongate dermal bones ; meta- 

 pterygoid present, forming the upper margin of the cheek bones 

 above the symplectic ; symplectic normal ; palatine and pterygoid 

 both present and normal ; the former with teeth ; primaxillaries 



1 Sixth Memoir, National Academy of Sciences, Vol. VI. 



