PIIYSOCLISTI. 3G7 



593. N. avocetta Jordan & Gilbert. 



Head, slenderer, its depth oue-uiutli its greatest length. Eye large, 

 oue-third the head, without snout. Length of pectoral scarcely greater 

 than height of anal, which is scarcely less than* tlie greatest depth of 

 the body, and more than the greatest depth of the head. Translucent; 

 belly with close-set dark spots, its lower edge and anal fin black, the 

 back abruptly white and unspotted. L. 22 inches. Head 10; depth 58; 

 depth of anal G4 in length of body. Puget's Sound; one example 

 known, differing in some slight respects from all Atlantic specimens 

 examined. 

 (Jordan «fc Gilbert, Proc. U. S. Nat. Miis. 1830,409.) 



SracLAss PHYSOCLISTI. 



[Tlie PhysocUstous Fishes.) 

 Air-bladder, if present, without pneumatic duct, in the adult. Parietal 

 bones separated by the supraoccipital. Ventral fins usually thoracic or 

 jugular, normally with 1 spine and 5 soft rays. Pectoral fin normally 

 inserted high, with vertical base. Vertical fins usually with spines. 

 Premaxillaries normally forming the entire border of the upj)er jaw. 

 Tail homocercal. (^uo-.^?, bladder; xhiaru:^ closed.) 



AXAXYSIS OF THE OKDEIl OF PHYSOCLISTI. 



a. Scapula suspended to the anterior vertebrae ; maxillary distinct ; superior bran- 

 cbihyals and pharyngeals present ; inferior pharyngeals not united; no 

 interclavicles ; body elongate ; ventral hus abdozuiual or wanting. 



Opisthomi, p. 

 aa. Scapula suspended to the cranium by a post-temporal. 



h. Lower pharyngeals co-ossilied ; lins without spines; ventral fins abdominal; 

 third and fourth superior pharyngeals much enlarged. 



Syxentogxathi, Q. 



hh. Lower pharyngeals separate (or if united, flns with spines and ventrals thoracic). 



c. Gills tufted ; superior branchihyals and pharyngeals and basal branchihyals 



Tcanting; ventrals, if present, abdominal Lopiiobuanciiii, R. 



cc. Gills pectinate, 



d. Superior branchihyals .and pharyngeals reduced in number ; ventrals abdom- 

 inal IlEMIFillANCniI, S. 



dd. Superior branchihyals and pharyngeals normally developed; ventrals mostly 

 thoracic or jugular. 

 e. Bones of the jaws not united. 

 /. Pectoral fins not pediculate, the gill-openings in front of them. 



g. Cranium normal AcANTnoPTERl, T. 



yg. Cranium anteriorly twisted; both eyes on the same side of the head. 



Heterosomata, it. 

 ff. Pectoral fins pediculate, their basal bones reduced in number and elon- 

 gate; gill-openings in the axils Pediculati, V. 



ee. Bones of the jaws co-ossified ; the dentary with the articular, and the pre- 

 maxillaries with the maxillaries Plectogxathi, W. 



