62 Memoir Sears Foundation for Marine Research 



readily recognizable. The Study Material is listed for each species; in most cases this 

 includes specimens from the many institutions listed. For easy and quick identification, 

 the Distinctive Characters^ as in the Key, compare the easily recognizable features of 

 one species with the others. Many specimens were examined in preparing the taxonomic 

 accounts, and the methods of measuring and counting the characters are detailed on 

 p. 68. 



The Descriptions are broken down into three major categories: (i) Proportional 

 measurements in per cent of length, (2) Proportional measurements in per cent of head 

 length, and (3) Meristic counts. Thus measurements for most of the head characters 

 (snout, lower jaw, etc.) are given In per cent of head length as well as in per cent of 

 length of fish. Following submission of this account for publication, a small specimen 

 of spatula, 49-5 i^rn (57.3 mm TL), came to hand; the measurements for this individual 

 have been Incorporated in the Description with figures enclosed in brackets. 



What is known of the life history of Gars in general and of the species In particular 

 has been culled from the literature and gained by direct observation and personal com- 

 munication with field workers. The Synonyms and References at the end of each species 

 account Include references to only those taken in salt water; these are not numerous, 

 because Gars for the most part frequent fresh water, and less commonly brackish or 

 salt water. 



Characters. Leplsostei are slender ray-finned fishes with well-ossified skeletons, 

 as in the teleosteans, but with ganoid scales (see below), an archaic character shared by 

 the polypteroids alone among living fishes. The arterial cone of the heart has eight trans- 

 verse rows of 4—8 valves each,i a number of rows greater than In any other living ray- 

 finned fish; this character also puts the Gars apart from the polypteroids. The caudal 

 fin has no prolonged fleshy axis, but all of the hypural bones that bear the fin rays are 

 supported by the upturned end of the vertebral column (caudal "abbreviate hetero- 

 cercal," Fig. 1 1), and the rear boundary of the fleshy caudal peduncle slopes obliquely 

 dorsoposteriorly, the latter character shared by Amia alone among living fishes. 



The vertebrae are completely ossified and opisthocoelus, I.e. posterior face con- 

 cave and anterior face convex, a conformation unique among living fishes though paral- 

 leled in some tailed Amphibia and in the thoracic region of penguins, gulls, and plovers 

 among birds. In the adult the pleural ribs extend from the vertebrae to the skin (Balfour 

 and Parker, 7: 387, pi. 28 fig. 72; Emellanov, 20: 176-180, figs. 8-10). 



The elongated snout, with nasal openings and olfactory sacs at its end. Is the result 

 of a lengthening of the ethmoid region, and olfactory nerves course through long canals 

 In the ethmoid cartilage (Regan, ^8: 447, fig. 3). The preorbital (lacrimal or maxillary 

 of some authors) is subdivided into a row of 6-8 bones that bear small, medium, 

 and large teeth (Holmgren and Stenslo, I0\ 474, fig. 363; Hammarberg, 29: figs. 41, 

 43; Berg, 8: 211, 414); the larger teeth are radially grooved at the base. The 

 Infraorbital sensory canal Is a prominent surface feature of the preorbitals In the early 



I. For an excellent illustration and for a table giving the numbers of valves in various other fishes, see Bertin 

 {2$: 1402, fig. 1005 B, 1404). 



