58 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



a. Dermal arjuatiire absent, oi- developed only as plates on side or back; vertebr;<! 



numerous (80 to 36); pubic bones placed close to scapular arch; spinous dorsal 



represented by isolated spines. 



h. Vertebrae anteriorly little enlarged; ventrals subthoracic, each with a sharp 



spine. 



c. Branchiostegal rays three; ventrals with one soft ray each; snout conic or 



but slightly tubiform Gasterosteid.e, I. 



cc. Branchiostegal rays four; ventrals with four soft rays each; snout tubi- 

 form AULORHYNCHID.E, II. 



hh. Vertebrpe anteriorly (first four) elongate; ventrals abdominal or near middle 

 of body, without spines, but with 6 (or 5) soft rays. 

 d. Dorsal spines developed, weak; body compressed, moderately long, with 



ctenoid scales; no caudal filament Aulostomid^, III. 



dd. Dorsal spines undeveloped; body depressed or subcylindrical, very long 

 without scales; caudal with the two middle rays produced into a long 



filament Fistulariid.e, IV. 



aa. Dermal armature superficial, developed anteriorly and especially about the back; 

 four anterior vertebrae much elongate; tail with its axis continuous with that 

 of the abdomen; branchihyals and pharyngeals mostly present (fourth superior 

 branchihyal and first and fourth superior pharyngeals wanting); pubic bones 

 remote from the scapular arch ; a spinous dorsal fin developed. 



Macrorhamphosid^, V. 

 aaa. Dermal armature connate with the internal skeleton and developed as a dorsal 

 cuirass in connection with the neuropophyses; six or more anterior vertebrae 

 extremely elongate; tail with its axis deflected from that of the abdomen by 

 encroachment of a dorsal cuirass over the dorsal fin; branchial system usually 

 feebly developed; a spinous dorsal feebly developed under the posterior pro- 

 jection of the dorsal buckler Centkiscid^, VI. 



Family I. GASTEROSTEIDAE. 



STICKLEBACKS. 



Body more or less fusiform, somewhat compressed, tapering behind 

 to a slender caudal peduncle. Head moderate, the anterior part not 

 greatly produced, but all the bones of the suspensory apparatus some- 

 what lengthened. Mouth moderate, with the cleft oblique, the lower 

 jaw prominent; maxillary bent at right angles and overlapping the 

 premaxillary at corner of mouth. Teeth sharp, even, in a narrow 

 band in each jaw; no teeth on vomer or palatines; premaxillaries pro- 

 tractile. Preorbital rather broad; suborbital plate large, often cover- 

 ing the anterior part of the cheeks, forming a connection with the 

 preopercle. Branchiostegals 3. Gill membranes broadly joined, free 

 from the isthmus, or not; gill rakers moderate or rather long. 

 Toothed superior pharyngeals 2; that of fourth arch missing or 

 united to third. Opercles unarmed. Skin naked or with vertically 

 oblong bony plates; no true scales. Dori^al tin preceded by two or 

 more free spines; anal similar to soft dorsal, with a single spine; ven- 

 tral fins abdominal, anteriorly placed and overlapped slightly at the 

 side by a process from the shoulder girdle, though not connected to 

 it, consisting of a stout spine and one or two rudimentary rays. 

 Middle or sides of belly shielded by the pubic bones. Pectorals 



