742 



Bulletin 47, United States National Museum. 



In the following analysis of families we adopt the arrangement of 

 families as given in Dr. Gill's valuable discussion of "the mutual rela- 

 tions of the Hemibranchiate fishes " in Proc. Ac. Nat. Sci. Phila., 1884, 154. 

 The osteological characters are largely taken from unpublished notes of 

 Mr. Cloudsley Rutter. We begin the series with the most general- 

 ized family. 



a. Dermal armature absent, or developed only as plates on Bides or back; vertebrae numerous 

 (30 to 36) ; pubic bones connected with scapular arch ; spinous dorsal represented 

 by isolated spines. 

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



c. Branch iostegal rays three; ventrals with one soft ray each ; snout conic or but 



slightly tubiform. GASTEROSTEIDJE, xcvm. 



cc. Branchiostegal rays four ; ventrals with four soft rays each ; snout tubiform. 



AuLORHYNCHIDiE, XCIX. 



II. Vertebrae anteriorly (first four) elongate ; ventrals subabdominal 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.E, c. 



drf. Dorsal spines undeveloped ; body depressed or subcylindrical, very long, without 

 scales ; caudal with the two middle rays produced into a long filament. 



FlSTULARIIDjE, CI. 



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 not connected with 

 the scapular arch ; a spinous dorsal fin developed. MACRORHAMPHOSID.E, en. 



Family XCVIII. GASTEROSTEID^E. 

 (THE 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 somewhat 

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

 prominent ; maxillary bent at right angles and overlapping the premax- 

 illary at corner of mouth. Teeth sharp, even, in a narrow band in each 

 jaw ; no teeth on vomer or palatines ; premaxillaries protractile. Pre- 

 orbital rather broad ; suborbital plate large, often covering the anterior 

 part of the cheeks, forming a connection with the preopercle. Branchi- 

 ostegals 3. Gill * membranes broadly joined, free from the isthmus, or 



* According to Mr. Rutter the gill formula is : 



The third and fourth epibranchials are present, but apparently grown together. The same is 

 probably true of the third and fourth pharyngobranchials. 

 The species examined was Gasterosteus microcephalus, GIRARD. 



