2. AULOSTOMA. 535 



pectoral and composed oi sijs. soft rays ; both tins are widely apart 

 from each uther, and theii' distance fiom the pectoral is two-sevenths 

 of that from the caudal. The form and position of the vertical fins 

 is the same as in F. tabaccaria. There is a series of feeble spines 

 imbedded in the skin along the median line of the back and of the 

 abdomen : these spines do not belong to the endoskeleton ; for if the 

 skin is removed, these spines foUow, and are easily detached from its 

 outer surface. They are evidently rudiments of the spinous portion 

 at least of the dorsal fin, which, in Aulostoma, is more developed, 

 the spines being free. 



Greyish, silvery along the lower part of the head ; sometimes a 

 seiiee of blue spots along the side or the back. 



The greater portion of the case formed by the bony shields behind 

 the head is fiUed by the air-bladder, the membrane of which is thin, 

 coating the interior surface of the upper and lateral shields, and 

 fijmly attached posteriorly to the muscular mass which commences 

 behind those shields. A portion of the stomach and the liver also 

 are enclosed in that anterior portion of the abdominal cavity. The 

 stomach is elongate, subcylindrical, and passes gradually into the 

 intestine, which is' short and straight to the vent. I observe only one 

 short pyloric appendage, enveloped by a portion of the pancreas, 

 which is situated along the whole posterior side of the stomach and 

 encircles its pyloric portion. The spleen is elongate, ovate. The 

 abdominal cavity is extremely narrow from the point where the 

 muscular mass of the vertebral column commences. The kidneys 

 are thick and very long, extending along the whole abdominal cavity 

 upwards to the air-bladder. 



A comparison of this species with Gasterosteus spinacJda will 

 show the close relation of the Fistularidce and Oasterosteidce. 



2. AULOSTOMA. 



Fistularia, sp., L. Syst. Nat. i. p. 515. 

 Solenostomus, sp., Klein Sf Gronov. 

 Aulostoma, Lacep. v. p. 357. 

 Polypterichthys, Bleek. Ternate, ii. p. 608. 



Body covered with small scales. Caudal fin rhombic, Avithout 

 filiform rays ; a series of isolated feeble dorsal spines. Teeth rudi- 

 mentary. 



Tropical parts of the Atlantic and of the Indian Ocean. 



The Atlantic and Indian species of this genus are so closely allied 

 to each other that they were confounded by Linne and the following 

 ichthyologists. MiiUer and Troschel were the first to distinguish the 

 Atlantic species by a separate name. These fishes have always been 

 described as toothless, in consequence of which Dr. v. Bleeker, who 

 saw the patches of rudimentary teeth, describes the Indian form as 

 new, creating a genus, Polypterichthys, for it. 



The species of Aulostoma show the same peculiar structure of the 

 anterior portion of the vertebral column as Fistidai-ia. These two 

 genera belong to one and the same natural family. 



