342 



SCANDIXAVIAN FISHES. 



SINENTOGNATHI. 



Malacopieriigian Eleutherognates wifh fJ/c loircr i>li(tri/nf/e<ils itiiitccL Ilodi/ coverciJ iritli a/cloid scales, the lateral 

 line set low doini and followinn a raised roir of distinct scales alonr/ each side of the hellij. Dorsal fin situated 

 on the caudal jiart of the hodi/, and the anal Hn analof/ous to if in sltapc and position. Ventral fins cdidiimimd. 

 Nasal cavities open. Air-hladder, irhen present, gener(dhi large and sometimes internally divided info cells. I'seudo- 

 hranchire f/la»dnlar and dverr/roirn. Branvhiostegal rags generalhj more tluoi 10. Digestive canal simple, straight, 



with scarcehj distingiiishalile stoinacli and n'ifhont piihiric appendages". 



Even in Johannes Mllleu'' this series of piscine 

 forms was essentially defined, in cli;! meters and contents, 

 as a distinct family, Seomhresoces, or, regarded as a sub- 

 order, Fhargngognathi malacopterggii. It was an extract 

 from the older genus Esox of Linx/eus and Cuviee, 

 which had, however, been previously broken up, first by 

 Rafinesque'' and afterwards bv Cuviek himself and 



Not only are tlie structure and function of the pharyn- 

 geal apparatus entirely different, the upper pharj'ngeals 

 being comparatively small, l)ut strong and closely set 

 with teeth, the lower also furnished with teeth and still 

 further strengthened by tiieir coalescence; but, in addi- 

 tion to this, the straight, but fairly ^vide, intestinal canal, 

 which, however, gradually grows narrower posteriorly, and 



BoNAPAKTE. The last ^vriter arranged tliese forms in | is without any distinct stomach, otters the most entire 



two subfamilies'', Belonini and Exocoetini, ^vithin the contrast to the winding digestive canal of the Mugiloids. 



family of the Pikes. Cote united tliem'" into a distinct (_>ne of the most remarkable characteristics of the 



suboi-der among the Physoclysts under the name of Synentognates appears in the smelling-organ. Tlie nost- 



Sgncntognathi. 



lu the external ap]>earance of the body these fishes 

 show a distinct resemblance to the Gray Mullets in the 

 more or less broad and flat dorsal side, especially at 

 tlie head, the greater part of which is here too, covered 

 with scales. The high position of the pectoral tins also 

 suggests this likeness, which is still more strongly ex- 

 pressed in the structvu'e of the skeleton. Here too, the 

 skull is broad and flat at the top. with excessively large 

 frontal bones and witliout ridges, but with the back- 

 ward jirocesses from the squamosal l)ones (ossa pterotica), 

 the mastoids {ossa epotica) and the lateral occipitals well- 

 developed and often elongated, as we ha\ e found them 

 in Mugil. The spinous processes of the anterior ab- 

 dominal vertebra' are also longitudinally extended and 

 contiguous. (_)n tlie under surface of the Imsilar part 

 of the occipital bone, sometimes in the middle as well 

 as on the sides, we find downward jjrocesses resemlding 

 the analogous formations in the Carps. 



In the other respects, however, the Synentognates 

 range themselves in sharji contrast to the Gray Mullets. 



" According to Day the genus >Scoitihrcsox possesses pyloric appendages 



'' Abli. Akad. Wiss. Berlin 1844, Pliys. Abh., p. 170. 



' See SwAiNSOX and Bi.eekek, 11. cc. Rai'INESQUE's work lias not been accessible to ns. 



■^ Nuov. Anu. Sc. Nat., Anno II, tomo IV (Bologna, 1840), p. 274. 



' Trans. Anier. Pliil. Soc, Pliilad., N. ser., vol. XIV, pp. 456 and 457. 



/ Cu'v., Vai.., //?>/. Sat. Poiss., vol. XIX, p. .3. 



'J L. c, p. 58. 



'' Proc. Acad. Nat. Sc. Pldlad. 18t;3, p. 27.3. 



'■ All. Ichth. I ml. Or. Need., toni. VI, p. Gl. 



rils are open cavities, situated just in front of the eyes; 

 and the olfactory organ itself is set on a transverse 

 swelling or dermal fold that rises at the bottom of 

 each cavity. 



In some of the species of the genus Hemiramphas 

 Valenciennes' found the air-bladder internally divided 



ft' 



into cells, calling to mind the similar formations in the 

 jjenus Amia : and Glnthek, who ranijed the Svnento- 

 gnates in close proximity to the Cyprinodonfidee, grounded 

 his opinion chiefly on the .sexual ditt'ercnce, first re- 

 marked l)v Valencucnnes", in those species of the genus 

 Hemiramphus, to a great extent fresh-water fishes, which 

 have subsequently been assigned bv Gill'' and Bi>eeisEu' 

 to the genus Zenarchopterus. In these species, which, 

 like the majority of the Cyprinodontidcc, are viviparous, 

 and in which the ova must, therefore, be fertilized within 

 the uterus, the males are distinguished partly by a 

 papilla ])ehind the xent and ])arth- by the advanced de- 

 velopment of .'iome of the rays of the anal fin (some- 

 times of the dorsal fin as well). These rays groxv longer 

 and thicker than the others, and sometimes ac([uire 



Wc have failed to find anv. 



